Repairing engines is probably not based on simple economics. The learning process and satisifaction of knowing that you can do it is its own reward like lots of other modeling activities. Bearings and gaskets are usually about $25.

It will be important to bench run the engine since there were a couple of questionable areas (carb barrel, bearing). It is remarkably easier to zero in on an engine problem when it is mounted to a sawhorse or picnic table. Also if it should malfunction or start to lock up the probability of catching the problem before damage is good. A simple flat 1/4 plywood engine mounting plate should be simple to make. The height of the fuel tank relative to the carb centerline will also be important.