I'm currently rebuilding a CJ5, and replacing the AMC 304 with an AMC 360 (here's my build thread: My CJ5 project . . . . .
I had originally planned on buying a complete rebuilt long block from a similar company that you're considering. However, I read quite a few opinions on the web about the possibility of a less-than-quality build on some of those engines. That put enough doubt in my mind that I decided that I would use a local machine shop for the build. I got advice at my local 4-Wheel Parts outlet as to a good machine shop, and met with them on Friday. They promised me a better-than-stock build. They are very busy doing performance builds, and I got the impression I will get a lot of personalized service. Plus, they have experience with AMC V8's, which is a real plus.
I'll be taking my heads to them this week, and the project will begin!!!