The one thing I notice are all the drag marks/scrapes inside the #1 crankcase, almost looks as though this thing may have tossed a rod in the past. The pistons seem newer because they only have two rings… Someone may have replaced the crank, or perhaps the “polished” some of the imperfections off if in fact the engine threw a rod. So, I would measure those crank pins very carefully along with the big rod ends.
Frank offers excellent advice by drawing attention to the crankshaft and driveshaft splines. Clean them up and examine the crank/driveshaft splines very closely. The last thing you want is to reassemble this powerhead only to discover the splines have spun/rusted away when you start the engine and the prop doesn’t spin!
