The cracking issue has been beat to death. Most of the cracks don't leak. There must be hundreds of thousands of Magnum heads on the streets today with the famous crack.

Of course if you have the $$$ the EQ heads are very nice. They can be had either Mag face or LA face.

http://www.aamidwest.com/enginequest/cylinder-heads/chrysler-magnum-head/

Now is the time for Blazin' Bob to jump in and warn you to get the heads either from EQ or a reputable dealer. There are lower quality Chinese castings out there. Caveat Emptor!

R.