Around here a used stock 402 might bring 450 to 500 .In that range. Question, why not build the 402?I've been told all my life it seems,that a big block breathes much better than a small block.LT1S10 and I have a friend that has a 67 --396-375H.P. camaro that ran in the high 120s in the 10s. That car was never used as a street car and is setting in his garage today with only 1122 actual miles on it. You dont see many 383s turning those kind of numbers.Although I have pretty much been a small block chevy man all my life I have been tempted to go that route myself, I have read several comparrison articles over years and I cant remenber the small block coming out on top very often. If You just want a 383 , go for it.