I had a bad #14 head (original to the car) that was just starting to mix coolant into the oil, but wasn't pressurizing the cooling system overnight. Removed the head, and it had really big cracks between all the valve seats, much worse than your junkyard head. I'll bet that just about every #14 head still in operation has cracks between the valve seats.

So you are taking a risk, given the cracks, but if you've got the time and the inclination, you may get years and years of service from that head.

However, I think you should repeat the test in a hot bath of 80 deg C.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC