I got this in a trade and had thought about using the engine elsewhere. After getting it running and driving, I decided to keep it together as a yard tractor. The engine is a B&S 20 HP (460777 1276 01) with pressurized oil system. First one of these I had ever seen.
I had to make new throttle and choke cables as the old ones were seized. Got the throttle in yesterday. Working on the choke. Have to reroute it due to the close proximity of the grille. It originally came in from the front of the carb. Too much of a bend for the cable, so I am making a bracket and lever to let it come up from the bottom. I'll have some pics later.
For now here's some pics I posted in the original thread.