Same engine top to bottom. I would double check that the CDI is the same via polaris browse just to be safe. Everything else will bolt up just fine. Those engines are a dime a dozen because of the issues with them. If you can afford it I would consider doing the oil pump upgrade option that they put on the '97-'99 XLT engines.
install it correctly with the correct jet settings that was used for the XLT as they maybe different then the XCR. As long as it has compression, fuel and everything is correct then yes. Those engines were not exactly known for there quality. Some had issues from factory some did not. There was the drilling of the oil hole in the crank, the oil pump upgrade and so on that they made over the years to improve the engine. When they are right they do run good. Just don't use aftermarket pipes, don't under jet it and you should be fine.
So I'm only a couple years into this '01 800 and it no longer starts. Trying to pull start is impossible. The cord can be pulled full but at an inch a sec. TOUGH! Spark plugs out, no problem it rolls easy. Is this a flooded engine or worse!?
So I have a 2000s rmk engine in a older wedge. It is a 600, I have 700 carbs, jugs, reeds, head, an pistons. Could I swap out the top end? If so what would I have to do to the jetting? Any knowledge is appreciated!