We used to consider .060" to be a minimum clearance between pistons, valves, and other potential points of contact on engines that could wind tight enough to float the valves. The chances of that happening on a stovebolt are somewhere between slim and none, so your engine should be good to go. "Milling", "surfacing" and "decking" are synonyms for the same process- - - -removing a thin layer of block or head surface to assure a good gasket contact, or cuttng considerably more for adjusting the deck clearance of pistons or increasing compression. Making radical changes in the block or head surface dimensions can affect valve system geometry so it's a good idea to do a test assembly and make sure other adjustments like adding shims between the rocker stands and the head won't be necessary.
Jerry
