The Briggs muffler is screwed to the top of that stack Bill, your probably right about the engine Tom, looking at the rust colour in the carby inlet throat, but you never know until you play, your new found looks solid.No, that's the air filter. I don't know the condition of the engine, but it might not be a terribly difficult restoration. The deck even looks good, best I can tell.
you are quite right Bill, a lot of Briggs came out with that flat long muffler.I should have noticed, my tiller has a muffler like the one on the top of the stack. As for the air cleaner, my lawn mower, with the Briggs and Stratton engine, has a muffler that looks just like the one on the seat.