I have a 383 w/modified TPI w/stock convertor and stock 3.23 gears. Right now I am running the stock prom from the 305 and the car is anemic. Can I just get an off-the-shelf performance chip for a 350(like performance resource) or will I need one custom burned?

 

you'd be much better off changing the chip since 305 and 383 will have much different of an ignition advance curve requirement and same with fuel curve. a 350 is very close on ignition curve requirement, just different on fuel requirements. if you find a 350 chip with some fuel pressure adjustments it would be considerably better than the 305 chip, but your better off with something burned for your engine.