Put clay on top of the piston near the eyelits cut for valve clearance. Reassemble one cylinder with intake and exhaust valves (use very weak springs if you have them). Tighten the heads using a couple bolts. Install pushrods and adjust valve lash. Using solid lifters if possible, or well oiled hydraulics if you must, rotate the engine crank through two complete rotations. Then remove the head, peel off the clay and cut the clay in half to check valve clearance. I recommend a little light oil to keep the clay from sticking.