Head, valve cover, exhaust manifold. Use a 4.0 head gasket. Heads with 7120 casting numbers are said to give the biggest performance boost. Here's a link to one of many articles on the subject found online. I did it to my CJ using the 258 intake and a MC 2100 carb and loved it. <img src="/forums/images/graemlins/cheers.gif" alt="" />
4.0 Head conversion