I wonder why it's mounted that way? The only explanation I can think of is the fuel tank of the Briggs doesn't clear the chute of the base. That's why old high arch Victas had then mounted that way and as a result an unsightly coat of soot formed against the rear of the base.
The seller would be better off finding a steel base to put that on. The left hand side of this cast aluminum base is worn also.
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!
I see quite a few mounted this way, but it is usually the earlier Briggs with the shorter crankshaft. With the longer shaft Briggs they are mounted with the spark plug to the front and a spacer ring to lift the motor up to clear the chute as MF said. Steel base Victa has the same problem MF, needs the spacer ring to clear the fuel tank
That one is already on a spacer and the reason it's mounted sideways is because even with the use of the spacer the fuel tank still fouls on the sweep of the arch. The sweep sits higher that that on a steel base.
Victa used a Tecumseh as a four stroke option on that base which obviously fits without clearance issues. That and perhaps Honda and the V40 must have been the four stroke options on offer.
IIRC the Briggs used on the early thumb latch base during the full crank two stroke era, had an exhaust that directed the gases side ways away from the rear of the base. Many owners or mower service shops must have just fitted the standard muffler when it needed replacement, causing the black coating.
Ahh, if only victa had kept producing the thumblatch catcher series, they would be in better shape today!