83 stock 305 cam sizing question

[nlauffer]

I have a stock, but rebuilt 305 in my 83 GMC.  It is a 4 barrel with stock intake and exhaust manifolds.  True duals without crossover.  Crossover is coming soon. 

My question relates to cam change.  I am wanting to up the cam size, but can't decide on how big.  I mostly want idle and sound change.  I like the thought of the Comp Cams Thumpr, but the lift is something like .510.  I want the choppy idle of that cam, but less lift.  New springs, roller lifters, intake and carb, and maybe some slight head work will be done. 

It would be nice to make changes that could be swithced over to a 350 in the future.  I have my eyes on a free one, just don't have it yet.

[Jason S]

Have you called Comp Cams with your exact specifications?

Things like a flat tappet vs. roller lifter, dual plane vs. single plain intake, axle gear ratio, automatic transmission (plus torque convertor stall) vs. manual transmission, headers vs. iron exhaust manifolds, exhaust pipe diameter, compression ratio, head volume/flow, racing vs. daily driver, desired sound, etc. all factor into the overall cam specifications. 

A hot cam for a 305 may respond very mildly to a 350, just as a hot cam in a 350 would be mild in a 383...