I'll try this again
Chevy:
SBC 265 inch to 400 inch all the same engine family
BBC 366 inch to 510 all the same engine family
348-409 (and she's real fine) sort of chevys first edition big block, little or no interchangeability
LS series aproximately 346 to 427 all they have in common with the sbc is the bore centerline. A great motor, which when stripped down the block is light enough to walk around with. generally considerred a small block
Mopar:
272 to 400 inch small block
383 inch to 500 big block (both hemi and wedge)
Ford:
Windsor family small block 221 inch to 351
Cleveland family small block 302 to 400 inch
Big block 352- 429 wedge, semi hemi and SOHC
4.6 5.4 SOHC, DOHC which is generally considerred the new generation small block ford
y-block 412 and ? fords first big block, little or no interchangeability.
These are the most common size engines, there are others. But as you can see a small block or big block refers only to the family of engines.
The easiest way to tech this stuff is either to run a claim series which is sort of self policing, or do like NASA, they run on a HORSEPOWER to weight ratio, at the end of the day the car gets weighed and dyno'd, if it's not within 10% the car is illegal. then there's the more common P&G which is most popular in drag racing.
Another NASCAR note, the rule book now states the minumum cubic inc h as 350, Waltrip ran something like a 319 inch engine and because it was more efficient with the restrictor plate it made the same HP as the others, but got way better mileage. That was before all the cars became identical along with all the engines and drivers, and IMO has gone completely down the crapper. The only difference between cars is a few internal engine parts and the headlight decals.