I’m thinking about taking a bge 6.4 and just replacing the pistons and rods
With a forged high compression piston roughly 13-1
Along with a decent rod
Carbed the engine and use it in my index car
Any reason not to use the factory crank ??

I am a fan of the factory cranks from the 6.4 They have proven themselves in forced induction applications to over 1,000 hp.

…. 1,000hp crank or wheel? and if so how much more have you seen?

1,000 hp wheel. Give David Weber a call from modern muscle xtreme. He will fill you in on what they can take. In fact, he collaborated with Hot Rod not too long ago and used a stock 6.4 bottom end ( albeit with his drop in rods and pistons) and it made 1,000 on the dyno with I believe stock main bearings, bolts, etc.

No, as long as it doesn't starve for oil(IE Oil pump caveats) you'll lift the heads on a BGE before you hurt the crank.