[Jeff Chambers]

With the heads bolted on, the only way to do it is to pop the springs off an intake and exhaust valve and replace them with weak checking springs. Then bring the piston to TDC on that cylinder and measure the available valve movement using a dial indicator. One of the bad things about this is that it doesn't show you where its contacting or how close the valve may be to the eyebrow, etc.

Doing it at you say by rolling it over gently won't do as you'll collapse the lifter an get a false sense of security. When you fire it up and the lifters pump up, you could have serious P-V issues.