It 465 81 yamaha

i just got a it465H. the person i got it from said didnt know what condition the bore was in, but wouldnt run but had spark... i got it home home and found out he had tried to do a rebuild on it.. mixture screw was all the way in. have got it running but overheats... not sure what else this guy has messed with. what steps should i go thru? the piston size is 0.0030 its max out, will have to resleeve next hone.. have looked at the main jet but cannot tell what size it is..can somebody HELP....