$50.
I'll send you cash right away...........
Seriously, it depends on the buyers needs,
if all the numbers check out and everything is machined properly:
$2500-$3500, to the right person, who needs one for their high dollar GTO ot T/A restoration. This engine would add that much value alone, on to the right car. However, there are not too many people in that situation.
For use just as a performance engine, $1500 - $2000......maybe more, if the buyer just loves those Ram Air heads. In reality, new aftermarket Pontiac heads are better than the old Ram Airs, but that name still means a lot to many people.