The cam you'll need at 10:1 is probably WAAAAY beyond what those heads can flow. 300 hp can be had with a stock cam, vortec heads, and 9.5:1. I'm doing it right now in a 350. In a nutshell, you have a big mismatch with those heads' flow and compression for a mild 300 hp combo
How about a head casting number? Sounds like 305 heads to me; small chambers, little valves.