Somebody got a super steal here, it went for $26,250.

Check the clearance, 99% of the time its the exhaust valve that burns. But if you're this far along remove both shims. If the intake valve seat is bad you will hear it in the intake, a bad exhaust will be heard in the tailpipe.

If you're using compressed air and a blowdown-gauge, BE Very CAREFUL, the engine will kickover violently if the piston is not at TDC.

also i would check all the valve for clearance when in there