"J" heads are everywhere Mike, you can probably find a set for less than $150. If you were closer I would let you have at all the ones I have stacked up.

2boltmain's suggestion on the newer swirl chamber head is a good one: less chance of detonation and a little more efficient.

But the real answer to your question would be to call one of the Mopar cylinder head specialists: I'm sure they have stuff that isn't advertised collecting dust and would be more than willing to rebuild them for you and do a "bolt-on" solution.