The issue with the exhaust port can easily be fixed by chamfering the edges. Remember, there is very little compression area affected by the scoring. Now the scoring on the compression chamber is somewhat subjective. If the cylinder is still an original bore, you can try cleaning it up with a cylinder hone up to next size. Replace piston and rings with next oversize ones as appropriate. Check for compression and if you get anything above 100 PSI that motor should still be good. While at it, chamfer all the inlet and exhaust ports on the rest of the cylinders to prevent future problems.