What did I buy?!

First off, it probably ain't got 9.5:1 unless it has the KB107s in it. BUT, since it IS a 71 model 360 (even though date coded 70, it's a 71 year engine), it DID come with higher compression than any other 360. Question is, are the replacement pistons correct for it? If not, then it probably has lower than stock compression. Really.....all this is conjecture unless you tear it down and SEE what's in it. If it really does have 9.5 it'll be an honest 350 plus HP. Nice find either way, since it is probably a thick wall casting. Yes, 600 bucks was probably a good deal. Since it's out, it wouldn't take much to yank the heads and just see. You'd know first hand then. Plus, you could put the thin head gaskets back on it. Just a thought.