Check /replace oil lines, filter, oil pump operation, carbs for sure, hard to tell if it was running lean, or if a piston ring broke and mangled up the top end.
For the break in, i always set my engine rich (and 50:1 premix WITH oil injection) That way the top end gets a good bath of oil and runs cooler. Heat is what kills a top end, or lack of lubrication. Once the majority of the break in is done, I tune the carbs spot on and have it running like a scalded cat.