I did a similar swap in my CJ6. The outside of the 360 shares the same dimensions as your 304, so if the 304 fit, so will the 360. In fact, most of the stuff on your 304 will bolt onto the 360. I stole the entire top end, edelbrock performer, from my 304 and stuffed it on the 360 when I rebuilt it. Just put in new internals. One thing to keep in mind when doing the swap from auto to manual is that the flywheel on the 360 is specific to that engine. You cannot simply get an amc V8 flywheel and throw it on. A good resource for your parts is Parts Mike. Either go to the web site or give him a call and he can walk you through most of what you need. He will likely have all the parts in stock and any advice that you might need.