Those heads are probably good, but are priced a few hundred higher than I'd expect to pay my builder. But you are getting a "name"...do they also warranty them?

Your local shop's charge for valve seats is very high.

With those numbers, yes, the machining was likely done. It's probable that all those changes to your engine were done at a very early date, when the even older parts were readily available. Matching gaskets may get interesting, otherwise I can't forsee any major reassembly issues.