HELP me

I just bought yesterday a (i think a1978) sears with 19.9 hp onan and the 3 speed plus hi/lo transfer mostly complete but i already got it tore down to sand and paint while i am waiting for a few parts ill post some pix but i need some help finding part #s for it. i am doing a complete engine re build and the only #s i have are model n52m-Ga 0199/3411A and serial J773286684 so any info will help thanks you can go to my album to see it if that helps also if anybody has one of these engines that is busted i may be interested in buying thanks again