318 hydraulic lifter preload.

On a totally stock factory engine, .010" variance between valve stem heights is actually pretty good. I have seen a lot worse on original engines that were still in good shape.

However, when you start talking about performance cams you open up a whole nuther can of worms. It is always best to get the valve stem height dead right. Any machine shop that cannot, or that says "this is good enough" is not a machine shop at all, IMO.

With today's modern equipment available, there is ZERO excuse to have any variation at all on a valve job. Anything less is unacceptable.

All that said, IMO, on ANYTHING with a non adjustable valve train you are asking for trouble if you do not measure for proper pushrod length. You can complain, but in all honesty, stock rocker arms and custom length pushrods are really not very costly. Both can be had well under 200 dollars total.