rocker shaft shims???

I don't know why they make stuff like that either. You really have to watch pistons because they vary like that and it affects the compression ratio allot. Will they return them and give you the ones you want? I know sending stuff back is a PITA but it would be better to have the right pistons than take that much off of the block and heads. If you do take .035 off the heads I'm sure you'd need to take some off the intake side of the heads also. And you'll most likely need shorter pushrods. So all in all the cost will probably be pretty close to the same.