Stop by your local auto shop and get some "Plasti-Gauge". It's strips of precision plastic line - like heavy fishing line - with a paper gauge. You put it on the top of the bearing and tighten the cap. Then take off the cap - the plastic will be smashed wide. The paper gauge then measures the clearance your have! Its a bit tedious - remember to lightly oil the bearings and inserts, and torque the caps accurately. But it'll give you great confidence that your clearances are good!
Also get a tube or so of assembly lube. Use on all moving surfaces. It's thicker than engine oil so it stays while you finish assembly, and provides good lubrication on initial start.
For head and valve assembly, get a small can of "Prussian Blue". This is a blue lacquer used by all machinists for precision assembly. Paint the valve seats when you think you're done lapping. Do a few more twists to see if all the blue is taken off the seats.
Last edited by 60sRacer; 11-06-2017 at 04:08 PM.