I bought four Springfield, Inc. receivers around the turn of the century and built up complete carbines using them and new/old stock USGI parts and Boyd stocks. It was great fun and very educational and I eventually sold off two and kept two.
The fit and finish of the Spingfield, Inc. receivers is very good and I had zero problem mating them to USGI parts. I seem to recall I paid $89.00 each for them in 1998 or 1999.