Swapping 03 Ram 4.7 with newer version?

My rad blew last week and of course I couldnt get off the highway, so the engine temp was pinned for quite a while. I got this truck used and I know of one instance where it had been run quite hot then. At the time it had a leaky head gasket but I was able to control that with a can of leak stop. This time though, the engine is really not happy, got another leaky gasket now, knocking when I accelerate...
I have contacted local wreckers to get an idea of cost/availability of a replacement engine and there wasnt much, and they are crazy expensive. My engine has 320 K km on it and the lowest the wrecker could find online was 265K.
Wrecker mentioned that only 03 & 04 are years of 4.7 engine that would work for me. Just wondering what all differences I would be looking at to try a newer 4.7 L ? Has anyone have any experience swapping out engines on an 03 Ram and using a much newer (less km) engine?