They are cores for a head nobody much cares about. The only thing they have going for them is they are closed chamber. I bought my last pair of 906s for $25, those are worth less. I'd say he should give them to you, to be real. Those are the kinds of things left behind at swap meets. If it makes you feel better offer $20 but that's just because you're a nice guy.

R.

PS: If you can do your own porting those can work pretty well on a 300 hp style engine.