If you rebuild the engine it will cost you $400 at least with the milling you would need to do if you do it right but the engine will last another 40 years if you take short cuts who can guess how long it will last. that will be parts and what all you will need some where around4 bills for a complete rebuild done right. you never know what you could run into once you tear it down.
well thats what I got into one 3 years ago. It was a complete rebuild boreing cylinder, valves, head rings piston and wrist pins.crank reground carb rebild. I think I covered everything olesalt