There are a lot of high quality machine shops in the country. If you are just going for machining work, there are more options to pursue than if you want the machining and the assembly work done.
Put another way, every species of engine has its nuances. Knowing those idiosyncrasies can make a world of difference in the acceptability of the final engine assembly. As an example, a retired Ford mechanic just assembled a completely re-machined 312 for an acquaintance. While the retired Ford mechanic may have worked for Ford for many years as a line mechanic, his familiarity with the installation of the rear main seal in a y-block Ford is questionable. Since initial start-up and tuning, after limited road miles, he installed a replacement rear seal last week. Unfortunately, it leaks worse than the first one he installed did.
Some of the 'things' that are good to be aware of in assembling a Ford y-block are not even in the Ford repair manual.
NOTE: I sent my acquaintance copies of all the information I had from Y-Block Magazine and Ted Eaton's web site before he set-out to have the replacement rear seal installed. I have reason to believe that the retired Ford mechanic did not read anything I sent before installing the second seal!
Regards,
NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York