J heads

I went to buy a 360 from a Dude and it wouldn't spin. I tried using a breaker bar but it would not move. So I found this 340 block close to me and wanted to check it out. The guy also has a 360 block and a set of j heads. I'm gonna try to get a deal on the 340 and heads. That's my plan at the moment.
Don't worry about closed chambers.
Aside from that, they're blocks...right?
Put whatever piston you want in it.