X-heads or J-heads on a 360 LA Engine

Roughly the same head sans valve sizing. If you have to buy the x's, leave them alone. Buying an X head, especially because people think they are special = $$$$, over running your J head, is money wasted because of a letter cast in the head. Performance difference between the two heads, when outfitted the same, is NIL.

If they both need refurbishing, put 2.02's in the J's and have the bowl blended and go.

If you can get the X's for $50, then yeah, buying them and sell them to someone that HAS to have them.