You need to find out what happened to that sbc, with a windowed pan, the block is probably trashed too.
What HP do you have, what impeller?
A roller suburban short block with decent heads, (64cc's, like vortec or 612's) aluminum intake, 750 holley, will make 325 hp all day long.
A ZZ4 is a good option, too $$$
Good luck,
Dan'l