Yeah, the SR-71 is a cool deal. I'm getting close to running mine on the dyno. From what I've seen so far, the combination of a factory 460 block and a set of SR-71 heads is a pretty easy way to make some serious power. Not as easy as with a BB Chevy, but I think it is easier than with a BB Mopar. The 429-460 engine doesn't have as many fans as the BB Mopar though. They didn't put them in very many muscle cars so the total market size is much smaller.