End play isn't all that critical- - - -"too much" is a lot better than "not enough". What is vitally important is the oil clearance- - - -the difference in the outside diameter of the crankshaft journal and the inside diameter of the connecting rod, which has the bearing material bonded to it. That is checked by using a piece of precision-sized plastic called "Plastigauge", or the old-fashioned way by putting a small piece of shim stock between the rod and the crankshaft to see if the crank gets hard to turn.
A "normal" oil clearance is between .001" and .003". I like to shoot for .0015" if possible. The clearance is adjusted by installing or removing shims between the connecting rod and the rod cap. If an acceptable clearance can't be obtained by removing shims, the rods need to be replaced, or the crankshaft needs to be reground to the next undersize, and rods of the correct diameter need to be purchased to match the crankshaft diameter.
Connecting rod clearance is very critical, and the engine is VERY unforgiving of errors. Be sure your machinist is well-versed in checking and adjusting bearing clearances!
The main bearings on a 216 or an early 235 are also shim-adjusted, but those bearings can be replaced. Much older engines, like the Ford Model T and Model A have poured Babbit metal main bearings, as well as rods. Installing a reground crankshaft in one of those engines is a really interesting process!
Jerry
