I have a 1977 300D with true mileage unknown. I took it recently to have the valves adjusted and compression checked. It came out with a compression of 340 to 350 on three cylinders and only 230 and 240 on #3 and #5. The piston rods are not warped, however the mechanic recommended to rebuild the engine - cost $6300. Could I get by just by changing the valve seals without going through all the rebuild process at this time?

Thanks for the advice.

Cris