I just thought about what you just posted.

It makes sense to why you removed the 1/4 inch as that moves the bumper up or down quite a bit.

Just using a rule of thumb anywhere from 1/2 to 3/4 of an inch more if you had left it.

My thumb rule says its ratios.
You take the distance measured from the axle to the bottom of the frame as the spring sits.
Divided that into the length from the spring to the bumper.
This will give you the multiplier to use against the thickness of movement.

I estimated two or three times by just eyeballing!

If my thumbs don't get me into trouble, my eyeballs will!
You can, Just ask my wife! (:-)

Phil

The slight tail down look is part of the design but mostly optical allusion due to the use of saloon rear door tops. Never actually seen a height of the front and rear of the roof listed though. Tail down after 20 pus years of being loaded within an inch of it's life won't have helped the rear springs so just replacing those is a good first move. There are various stiffness ratings, the softest being those used in conjunction with the Nivomat self levelling rear shocks. Did they fit those on USA spec cars? They are VERY expensive to replace, if you can even find them, but if you fit "normal" shocks the rear will then sit down at the back a bit. Comfortable though if you are normally 2 up and carry very little in the back. Your dog won't mind. As said, the stiffer shocks are best left to those who routinely carry 500lbs in the back or do a lot of towing. Will make for a rather uncomfortable journey if doing lots of miles with the stiff or full stiff springs.
Fitting a full set of GLT front struts and springs will lower the front of the standard wagon and help to level it up a bit. GLT or turbo FRB a good move too.

The spring is 5" in diameter -- the metal cup (hat) it sits in accepts a rubber seat to isolate noise from the spring. The backside of the metal cup that sits against the chassis and has the hole for the bolt that holds it in place is about 3" in diameter. He put the puck between the backside of the spring hat and the chassis. I did the same thing with 1" aluminum - about 2.5" in diameter - to raise the back of mine which sat far too low with IPD sport springs.
--
82 242 5.0L; '10 Cayman S; '15 Honda Fit

I have used solid aluminum cylinders 3 x 1 1/4 inch thick under rear coil springs on a 240 sedan 1981. Worked well until it died with rust at 415k km.

I have been using the same setup for 15 years on a 1982 but 1 inch thick instead. I now find it could be a little higher and I must say I have a fair size tool box and 30 lbs spare parts in the trunk.

I use grade 5, 3/8 inch galvanized steel bolts, nuts that have nylon so they wont come loose. I use plenty of heavy grease to fill all the voids.

Only bad thing with aluminum, it does corrode/flake on the trailing arm with time. Never had to remove it though.