I just finally got my engine out of my 85 lt org everything all stock even stock bore but the swing arm is beat **** in 5 spots carrier is so beat up won't even hold a barring there is a weld on the frame "looking into grabbing a yfz 450 frame for front clip" the weld is where the right a arm is good brakes good wheel bearings plastic is stitched only payed 250$ for the quad and the oil seals are bad so I took the head off tonight looked good except a brown like burn mark under the rings? Maybe should I replace the rings?? Staring to polish the motor should have more pix soon

If you stick with the original frame (weld and all), be sure to reinforce the upper shock mounts.
It's a very common place for the 85-86 frames to crack, right behind the shock mount...if you look close there might already be a crack starting there.
The simple solution is to run a bar or tube between the two shock mounts so they won't bow inward under load.
A YFZ450 front clip is pretty involved, be sure that's what you want to do and that you have all the tools needed beforehand.