Ooh lord, someone stuck a Tecumseh on that classic base! Never seen that before. Judging by the orientation, it shouldn't be too hard to fit a PowerTorque to it.
Proof's in the pudding. Unfortunately, you don't find many mowers on the Central Coast, or at least I'm missing out. May have to start hunting.

Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!