Hey guys. I was looking around on craigslist and I found a 1975 Olds 455 with the "J" smog heads. I looked it up and it says these are pretty low in hp making around 200 hp. But I have a 71 455 that I have already bought. I was wondering if there would be any gain if I were to purchase the 75 but swap the heads. And if so how much of a gain. I am not expecting a big amount but anything is better than 200 hp from a big block. I was just thinking of taking this route because the 75' was built by Joe Mondello and is in running condition. And my 455 has not yet been established as a running condition motor. Anyway... thanks for any feedback I can get.