It's hard to tell from the photos... is part of the gear reduction housing integral with the crankcase cover, or is it completely separate?
Either way you'll probably want to replace the crankshaft... the gear reduction ones don't stick out very far and have a gear shrunk onto the end.
If the reduction housing (or the inner half of it) is integral with the crankcase cover you'll need to replace the cover too.
If you plan on using it on a snowblower, keep in mind the chute control rod on many machines occupies the same space as the fuel tank on that engine!
~1994 Ariens 924084 (ST1032) "papa bear": restored, re-engined, real nice!
1991 Ariens 924050 (ST824) "mama bear"
Toro PowerCurve 1800 "baby bear"
Be alert! America needs more lerts.