Tolerance of water pump play?

Some of the bolt holes are open to coolant or crankcase oil. I coat the threads w/ Permatex "gasket sealant" (purple, alcohol-based). I bought stainless bolts for the short ones and chromate for the long ones, at Ace Hardware. Good your timing cover isn't pitted. On my 273, it was almost corroded-thru to where coolant would have flowed into the crankcase. But, timing covers are still available and not very expensive.