I have a stock rebuilt 85 roller 318/833od/323gears in my 47 desoto. It has/had a 600 Holley, wieand stealth intake, block hugger headers, 2.25 dual exhaust/xpipe, magnum heads and a reground(bullet) LA roller cam with .436 lift. It seems to be out of steam very early in the rpm’s, like 4500. I think the stock cam would be the major set back to any combo. I know roller cams are pricey but I would stick with the roller setup and get an after market cam.