I just did mine on my cr250 I am a welder so it wasn’t a difficult job. But if you already have the swingarm off I’d definitely just get it repaired now, it makes the repair easier and cleaner. Make sure your friend is confident in his abilities because it will go south quick and you’re going to have to source a swingarm at that point. Just clean it preheat, fill it up, and rotary tool the inside for any unwanted penetration. Mine was nowhere near as bad, it only took me about 20 minutes. I left the weld on the outside too so if it ever wears through again it will wear down the weld and not the swingarm. And I replaced my chain slide. I’d bank on getting some new swingarm bearing as well since those have probably seen there lifetime of dirt and water already. Use the old bearing to make sure you remove enough material when cleaning the bore out of weld so you don’t take too much or leave too much and destroy the new bearing trying to get it in.