383 engine with the heads on, engine in the car. Heads are the 346 kind.

Do I have to have the cam in to check? I have a dial indicator and a valve spring remover, and a weak spring for checking. Never done this before, and really don't know how to.

The cam that I'll be installing has a .518/.518 lift. My concern is that the heads have been milled 0.030", flat top pistons are 0.020" in the hole, no valve reliefs. Running steel shim head gaskets. Stamped steel rockers are virtually never 1.5:1 ration, more like 1.45:1 ratio at best. With 1.45:1 real ratio the lift would be like 0.490" in reality.

I know I need to check piston to valve clearance. My question is, does it look good that I can run the "518" lift cam okay? I'm concerned about clearance.