You often are better off buying a good core to work with, but it’s difficult to actually get one that’s good from people online who don’t know WTF they’re talking about.
I paid $70 for the head, but it’s got a couple bent valves and one seat is nicked. I’d have to get my $70 back, plus whatever work was needed to make it new again(valve job, cleaning, pressure testing, surfacing, etc)
Machine shop information here: www.huntsmachine.com