I cant remember off the top of my head if this applied to the powertorque slaskers, but some of these mowers use an engine with a longer shaft, which would make it difficult to swap engines. if this is the case with yours, if the engine has sound compression and spark, just try restoring it, its a normal pwertorque from the plate up, it just may have a longer shaft underneath.
I may have some diagrams for this machine at home, i will check tonight.
the blade system is belt driven by a pully at the end of the crankshaft, its not to much more complicated than a normal victa 2-stroke, just bigger and belt driven, it's not even self propelled, so no gear box to worry about.
with the missing wheel, try comparing it to the rear wheel off the back of a mustang, i think it might be a match.