I have a Crower 271HDP in a near stock 383. It really needs a slightly higher stall converter than stock. It seemed a bit soft below 2,500 RPM but that is at my 5,000+ ft altifude. At sea level it might be better. I thought it was just too much of a comprimise cam. Just slightly too big hurting low end (with stock converter) and although it pulled smooth from 3,000-6,000 it did not pull as hard as something like the Mopar 284/0.484" cam. I never tried advancing the cam which should have helped the low end torque. I may try that in the future as the engine is on the stand, and I was going to put some closed chamber heads on it to get more compression.

If I was looking for a cam to work with the stock converter, gear, compression and such then I would keep it mild and use something like the Hughes SEH1620BL cam.

On the 383, if you want to use a large cam, be careful with using the Speed Pro / Sealed Power L-2315 piston as they don't have any valve reliefs. Also, with greater than 0.500+ cam lift, might want to use adjustable rocker arms.