340 vs 340.

I bet the 474 cammed engine will beat the 508 cammed one.

If the heads are stock with the 508 engine and the 474 have work, no brainer, 474. If the 508 or 474 are installed ahead a bit, even more than recommended, that will help that mill down low/mid range for sure.

just my experience with the 508-509 cam... the 484 is just as good until the last 500 or so of RPM range. I'd rather have the 474*480*484 cams than the 508 one. Unless the smaller cams are the horrid 114LSA. :)

There are so many variables here.