I'll jump in here as I also have a fair amount of experience with reviving long dormant motors. First I'll address what should and shouldn't be done. Suggestions to not start a motor periodically while in storage are well founded if--when starting the motor you simply run it for a few minutes. The procedure that Michael Yount follows is good, taking the car for a long enough drive to thoroughly bring all components to full operating temperature. What you have done by cranking the motor periodically by hand or starter is also beneficial.
I would not be concerned over finding piston tops with caked on carbon as those deposits indicate the motor was never run hard enough to keep the pistons clean when the car was still on the road. What I would be concerned with is the possibility of stuck or frozen rings. I would squirt ATF into each cylinder--3 or 4 good squirts. If you have a compressor good, but if not purchase or borrow a small portable air tank and attach a blower tool with an extended tip. Hold a rag over the spark plug hole to protect yourself and the surroundings from blowback and give each oiled cylinder a quick blast or two of air to spread the oil within the cylinder. Put the plugs back in--they don't have to be fully tight. Let soak and repeat after a few days. A couple or three such applications should be enough to get ATF down to the ring grooves.
When you are ready to actually start the motor I'd leave the plugs out, drape a rag over each plug hole and with a fully charged battery crank the motor until (in 15 second bursts if necessary to avoid overheating the starter) the oil pressure light goes out. At that point replace the plugs and fire it up. It will probably smoke like a chimney but let it run at idle or idle plus a bit. Eventually the smoking will diminish (unless there are already broken rings). When you take it out for its first drive go easy with a light throttle. To give you encouragement I'll relate my greatest success. I did these procedures on a Triumph GT6 that had been stored in a damp stone garage with a dirt floor for 10 years. The motor was completely seized so I could not turn it from the crankshaft front pulley bolt. I had to remove the starter and slowly work it back and forth by prying on the flywheel teeth until it would make a complete turn. That took the better part of a full day. With it ready to start (fresh gas from a remote container and the oil changed) it fired up - fogged up the immediate area with smoke (luckily our shop was in a wide open area with no residential neighbors). It took a number of hours of running slowly before the smoking diminished-but it did. Good luck (not said sarcastically) -- Dave

Thanks.

I'm torn about keeping the car. It's in great shape, both when I put it into storage and since. Definitely a one-of-a-kind. Part of me feels guilty about using it as a daily driver (LOTS of bad drivers who might hit it and bulky to park), the other part guilty about having it as a garage paperweight (fun to drive as a stick shift). My family is giving me flak about wanting extra garage space (I wear the pants in the house - the title to the house says so, LOL).

The car is SO easy to work on compared to my Toyotas (well, the timing belt was harder to do than on my B230F/1988 244). However, there are rarely junkyard donor cars.

Over the past 15 years, I have collected parts. I now have a spare, rebuilt 5-speed transmission for it (got an A in the class), numerous almost new tires/rims from my now deceased 1988 244, and most importantly spare CIS fuel injection components and CIS diagnostic tool/hose set.

If selling, I would smog it, get it appraised, then listing it for sale. It's definitely the right car for a collector.

I get 20-something mpg vs 35 mpg with my Toyota.

Idiots tailgate me in whatever I drive. A few weeks back, I test drove a Toyota Tacoma. An idiot in a Tesla cut me off, just a few feet from my rolling over him, while jerks in SUVs were tailing me on the freeway.

On the other hand, I have a Toyota that was burning oil and now has metal in the drain plug, signifying that I will need to look for another daily driver. I'm sure that it should be fully insured (collision/comprehensive).

My mechanic, who is walking distance from my house, had a bad experience with fixing my 1988 240's parking brake. He refuses to be my backstop on any further Volvos I bring him. He will gladly work on my Toyota, which I loathe doing timing belt/water pumps on.

My Toyota requires fewer repairs than my 1988 240, but I myself can do most of the repairs on the 240. I also have a CIS diagnostic tool (looks like an octopus with all the hoses).

Thoughts?

I have done a piston soak once on a 8 hp Brigg & Stratton 4 stroke motor.

It is on a wood splitter hydraulic pump. I loan the machine to a person who ran it all day long without checking oil level every 2 hours as I instructed. Eventualy the motor stopped.

I purged out what ever was left of the black oil and filled it to level. Then the suprise was that it was burning oil like hell. I could see the blue smoke downwind at my third neighbor.

Obviously the rings were seized in their piston groves. This is and old motor, I could hardly crank it by hand. A motor that has no wear would freeze hard and would never move, possibly has a groved cylinder wall.

I removed the spark plug and sprayed PB Blaster and cranked it to move the piston. Did that may be 10 times over 2 days. When the engine started it smoked heavy for 10-15 seconds and got slowly back to normal.

I had to repeat the PB Blaster every time I use it since 5 years otherwise it does not stop burning oil after 10 seconds.

I do not have competence to indicate you what is the best treatment for your engine, but I myself would not run it long if it starts burning oil. I would go to a treatment to free the rings.