There is one more issue that has not been mentioned - the valve spacing varies a bit from stock CJ heads. It's not drastic, but you do need to pay attention to your rocker arms when you install them. They will likely need to be shifted side to side to line everything up. This can be accomplished by placing shims as needed between the rockers and adjacent stands to slide the rockers over on the shaft. Erson makes a very nice rocker setup and sells a shim kit to go with it for use on the Ebock heads. You can also buy rocker arm sets that have some offset built in - can't remember the name of the guy who sells them but he is on e-bay all the time. I assume you will probably end up with a RPM manifold as it is an excellent street manifold and the price is much easier to swallow than a repro med. riser 2x4 piece. At any rate, check your pushrods for clearance within the holes in the manifold. They sometimes conflict.
You will be pleased with the heads, they are overall very nice and perform well. You do need to pay close attention to these items though or you could be setting up for trouble. If you need to get the smaller chamber heads for the exhaust pattern, don't worry about the compression. As long as you stay less than 10.5:1 you should be fine because the aluminum eliminates many of the problems that come with high compression. Also DO use the studs for the stands. Otherwise you have to put extra washers under the long bolt, and that is the one your
oil comes up through. You don't want to take chances messing that up. Drill out the
oil return holes and install restrictors in the
oil passages. Don't try to use your factory head bolts, you will quickly realize you cannot get a socket on some of them. You need to buy the Ebock head bolts because they have a smaller head (I think this must be a racket on Ebock's part) and be sure to use washers under the head bolts to protect the aluminum. I know I threw a lot of information out there, but if you are doing this for the first time there's no way you could know all these tips and I wish I had known all of this the first time I installed a set.