Need opinions on cyl.head problems

I have a 2000 xj with 72,00 miles and bad head gasket, head is 0331. When I removed the head I noticed that the head bolts between 3-4 were corroded from antifreeze being on them. Since the 0331 has such a bad history I went and pulled a 0630 and took it to get it checked. Turns out it is cracked, the guy at the shop checked the 0331 and can't find a crack.
Could the bad head gasket cause the corrosion on the head bolts? Is it worth the risk to put the 0331 head back on? I have a wrecked 2001 with 125,000 miles on the motor. Should I just go ahead and pull that motor and stick it in my 2000?

Your 0331 head definitely DOES have a crack and the corrosion of the head bolts between the no.3 and 4 cylinders is in exactly the place where many year 2000 have cracked. The crack is probably only hairline so your mechanic can't see it with the naked eye, but believe me you won't wanna risk reinstalling that head.
Source a 7120 head from a junkyard and have it magnafluxed for cracks and checked for flatness. If it turns out to be OK, port it, bolt it onto your engine, and enjoy the extra high rpm breathing.