1) When measuring jugs and piston fit, torque plates are a must. Not a recommendation.10k miles. I measured piston to wall and with bore gauge we are .002 off and with feeler approximately.003 or .004
2) if you can get a .003 blade into that jug and piston w/plates, its time for a machine shop.
3) Never trust reputation from a machine shop. Check everything once its back on your bench. **** happens, even in the best of regulated shops.
Past that, measuring jugs is 1/2 technique and 1/2 tool quality. Same goes for pistons, fact is some pistons are very difficult to measure without a jig. A blade in-between the piston skirt and the jug is your best bet for a done at home job.
All of these are only as good as the person using them. And if you look closely, none of the mic's are set up to measure pistons atm
But this right here doesn't require more than a entry level of skill to sort out. Just a good set of 12 inch blades that go all the way down to .001 But you do have to have torque plates. There is just no way to do it correctly without them.
So with the set up spec on a TC jug/piston being .0014 to .0025, you are headed back to the machine shop. I might mention that with the piston skirts being so short on TC's, there is very little margin for error. The discard point is .003.
So I'll say this one more time. You need to to seriously consider a crate motor. Even with that you are looking at dropping the oil pan to either clean of replace it and if it has an oil cooler, all of that needs to be disassembled and cleaned with any hoses and the cooler taking up residence in the waste bin.