I would suggest you to look at first for the motor is free and let turned without plugs from hand,then take a look to the plugs for theyr face,
when all looks good,named no old burned water or oil is visible, then I would pull the dist and turn with a drill maschine the oilpump for prepressuring all bearings,for that pull the valvecover and look for oil is coming there on the shaft.the outside tube in front of the motor
If all is good to this point i would assemble all,fill up water,clean the carb, check the ignition for working and give him a starttrail with fresh gas.
Then you can look whats for noises, oiling,smoking , or what else, then i would decide what is to do.
If all is ok i would run the motor carefully and look whats happen in the next time.
and then -- don't fix running systems -- ;-) .
Its an 3 speed, you must think for a glueing clutch is possible.
If i remember right the rodbearings 48 have babbit inserts yet , they start with insert bearings 49.
If you have luck, they has changed the rods at the last overhauling to the new with inserts.