Steve,

I have a '90 240 w/o air, and the factory belt size is 9.5 x 938, which it sounds like you've already tried. The pump mounting bracket is bolted to the block using the uppermost 3 holes, which on yours is most likely occupied by the A/C compressor. Also, the P/S pump is driven only by the crank pulley, not the crank and water pump like the two alternator belts. I'm not sure how your A/C belt runs, since I {sigh} only have '4/60' air conditioning.

You should be able to roughly measure the required length by running a small rope around the pulleys, and getting your local auto parts guy to fix you up with a belt of the measured length and the same 9.5mm width (or whatever width your stock pulleys require). Alternately you could tie the rope in a knot and the previously-mentioned auto parts guy can read it on his belt measuring gauge thingy (looks like a thing to measure shoe size).

Worst case is you might risk buying two or three belts until you get the perfect fit. If you're lucky and your auto parts guy knows you well, you might be able to try them out in the auto parts guy's parking lot and simply exchange the ones that don't fit.

Other than that you should be fine. It's not a good idea to run an A/C compressor once in a while to keep it from seizing up, but since yours is already hosed that's not an issue. But on Volvos with LH-Jetronic fuel injection, don't remove any of the wiring. There is an input into the MFI computer from the A/C, and the computer might be tricked into trying to compensate for an A/C load that doesn't really exist.

PS - Once you find a belt that fits you might want to post the size here for others to use.

[Nice rhyme, btw. Must be getting close to Christmas. Too close.]

Good luck.