Compression on 3.8L engine?

Can anyone tell me what the typical compression figure should be for a 3.8L in an '87 Bonneville? I am getting 175-180 on all six cylinders. This seems high to me. My Haynes manual only says 100 minimum. The tops of the pistons look clean. I just replaced the timing chain and gears after the nylon teeth stripped off the original gears. I'm unsure whether this is an interference engine. But with good compression on all cylinders, I don't think I bent a valve. The real reason I am looking for problems is that it was overheating on me. Blown head gasket? Again, with those even compression numbers, I tend to think not. New radiator, so thats not the problem.

Can I get a little help here? Am I chasing ghosts? One additional reason for the overheating could be that the trans was stuck in 2nd gear. I replaced it, so that should no longer be a problem. I have not run it since replacing the trans. That may have fixed it, but if the engine needs more work, I would rather do it while I have the engine out of the car.

Thanks in advance,

Glenn