Pontiacs came with fairly tight clearances. 67 rod and mains were 0.0005-0.0025/0.0002-0.0020. Some say the tight clearances were cause of overheating problems. I don't agree. Racing and hot rod guys think you should have 0.0035+. I put mine in the middle at 0.0025. I think that gives enough oil flow through the bearing/journals to cool, supply enough oil to maintain a good wedge and still have oil pressure at a red light in hot weather.

If you are getting ready to assemble and measure you must already have the machining done or are checking before reassemble. If you get clearances in the range Firebob stated you should be fine.