Rick, your cars are running almost 400hp on two barrels? That's impressive. What other restrictions do your cars have? The cars in the Hobby Stock class at a track near my house can run any size engine as long as they're all iron and run iron intakes and factory iron exhaust manifolds. There is a $1000 claim but nobody abides by it. I've got a 350 in the car I'm working on and I'm going to get my butt kicked by all of the 383s and 400s most other racers have out here.
Casper, as far as your question goes. Do as the others have already said and drop in the biggest engine you can. Also, I've been told to run lots of compression. If you're limited on compression then run the max allowable amount. The 350 I have now has about 11.9:1 compression but I'm thinking about tearing it back down and shooting for closer to 12.5:1. You're gonna have to run race gas. It's expensive but hey, it's racing and racing isnt cheap.