Do both, because chances are you're going to need a bore from all the shit that blew off your piston, also I'd clean the bottom end out as much as possible when you got the top end off.. If it didn't idle, part of that could be because of the airleak or possibly your pilot jets were wrong, maybe your carb sync's were set wrong... there's a few things that could cause that. I'd get a fresh bore, order a new top end, clean the bottom end out(drain oil and use your gas/oil mix that you put in the gas tank to clean out the bottom end, then drain that as much as possible mix out of your cases). I'd also fill with oil, drain again, and fill with a good lower end oil. After you get the top end on, I'd worry about getting an idle, then leaks, then its time to ride again!