In my '52 3100 project (S10 Chassis) I am seriously considering running a 5 speed trans instead of the 700R. Will any SBC flywheel bolt up to my 292? It is a reman engine pulled from an '84 3/4 ton. Casting numbers shows it to be a Mexican block from somewhere in the 80's if that makes any difference.

You will need to make sure whether you need a 153 or 168 tooth version (likely the 168) and whether you have 7/16" or 1/2" bolts attaching the flywheel to the crankshaft. It is not a big deal to drill out the flywheel if you have the 1/2" bolts. Either way you will need longer bolts going from a flexplate to a flywheel.

2 things first be sure of the bolt size,Redrill if needed.And be sure you get the flywheel that bolted to the Old style crank Not the newer one peice rear main seal Their is a difference.

External vs internal balance? So not from a 400?

Correct - 85 and earlier 350 or smaller cid v8 flywheel. The holes will need to be drilled for 1/2" flywheel bolts. This does not need to be machine shop precise, you can do this at home as the holes do not locate the flywheel, the center flange does.

Some cranks have one dowel pin..some have 2, and some have 3. I would expect your "made in Mexico" will have 3 dowel pins..

His will have 1/2" bolts and 3 dowel pins. All Mexican blocks are newer and have these features.
I do have a extra 168 tooth 292 3 dowel pin flywheel. Tom