What would you build if limited to 372ci - with boost as an option

That's shorter than a small block, that would be unreasonable lol, nearly 1 inch shorter.
The stroke you mentioned 3.100 with a 7.100 rod bbc journals and a 1.320 ch piston would work with a standard deck height block with .010 to deck square.
Fairly lightweight and rev to the moon, put some -1 or bigger heads with a tunnel ram, nitrous and 2 hair dryers.
This is interesting. I was looking at my 383 and run twin 72mm turbos, but under 372 would be a better class. No nitrous as that goes into a Fuel class.