Top End Rebuild??

I have a 2008 Can Am Renegade 800 that has some issues. This is what was happening when we were riding for three days at Hatfield McCoy trails:
1. was leaking coolant from the water pump, replaced the gasket and was still leaking so thought it might be the seal
2. coolant leak randomly stopped leaking and kept coolant
3. oil started burning, completely burned through all oil. Found a quart out on the trail and put it in and that lasted about 45 minutes of riding back to cabin. Started smoking pretty bad so stopped and drove to get two more quarts of oil to put in since we were close to the store by that point.
4. Put the two quarts of oil in and tried to make it back to camp. Thick white smoke was coming out of muffler and it wasn't keeping in the throttle when trying to baby it back to camp so we stopped and towed it (finally).

It's definitely knocking a little. It will start up fine and run and doesn't blow white smoke right away.

I'm comfortable rebuilding the top end, but I'm not sure how to tell if the top end is the issue or not? I really don't want to pay a shop to tear down the engine just to end up paying for them to rebuild the top end. I've heard that the bottom end rarely has issues.

Any opinions would be helpful.