Is the machine shop truely your problem

There are lots of engine builders and auto machine shops, at least in this area, who have never used anything except O.E.M. type parts for the "grocery getter" type engines they have rebuilt for 40 years ... with maybe just a few and far between aftermarket performance part.
You know, those places that simply have used a "one up" camshaft or an aftermarket aluminum intake manifold, valve covers or oil pan.

When they get out of their "element", it may become a disaster.