i have a 305tbi (soon to be carbed) with a 5 spd, and i want to get the biggest cam, that will still be semi streetable. what hp could i expect from that size with a 650cfm double pumper, and open plane manifold with headers. any help would be appreciated

 

The biggest cam you can install is 21¼" long. As for the lobe sizes, you'll have to provide a lot more information before anyone can even make an educated guess.

Heads, piston design, valve sizes, rear gearing, intended mode of operation, whether you need power brakes, and many other questions have to be resolved first. If you are near a newsstand, look through the latest copy of Chevy High Performance. There is a section on camshaft basics that might help you decide.