Hey man, like said in an earlier post, check out the bore. If its not scratched up at all at least measure it out and make sure that it isnt egg shaped or anything. Typically if there is a ridge on the top of the bore then it will need boreing. At a bare minimum hone the cylinder if your gonna get a new piston, otherwise the rings will not be able to seat. If it needs bored out only go the minimum amount needed, it goes in .020 incriments on a 300. going straight to a .080 over piston wouldnt give you enough more HP to notice rather than a .020. High compression is the way to go if your loking for more HP. Wiseco makes good pistons that I think go up to 12.5-1. If your gonna put a cam in it there are many differant options just do the reserch offered by the cam company and get the one that fits your riding conditions. Cams start around 100. Dont know about around you but I charge 35 for cylinder boring here in central michigan, probably ranges from state to state. Pistons start around 100 depends where you get it. You will need the piston before you can get the bore done. The machinist will need when boring the cylinder.
Just got a new dyno, callin it my new baby boy.
Honda 250R
Willy built motor, 100% custom
personally built 3mm stroker crank
long rod
ZRT piston
specially cut reeds
Major head work
Major cyl. work
Cases cyl all matched
2000 CR250 stator and ignition
Much more motor work
Basically stock chassis Shortened shocks