360 Magnum teardown

I have a 02 360 that came out of a van with approx. 150,000 miles. I started taking it up removing intake, exhaust and heads. With all the talk of cracked heads is there any physical way to tell if the heads are cracked. There was no water on any pistons and all seem to have an even coating of carbon. At this point I don't know if I will reuse them or go with an aftermarket aluminum head. Will the aluminum heads allow me to use 340 exhaust manifolds? I'm not an advocate of headers due to the problems they create, longevity installing grief etc. . Thank you in advance for any help.