Parts for old mower engine

[lavatan]

The problem is that Briggs filed bankruptcy and was brought by a financial investment that is killing off all the slow moving items. And jack the prices on every thing Briggs sells.

That's also a problem. I didn't know that. I would just put a new engine in it but the problem I have is this mower is kind of a unicorn in that it uses pulleys on both sides of the crank. As the engine sits the top pulley drives the front wheel that spins 360* and the bottom drives the blades. I'm not sure if I can find an engine that would accommodate both.

 

[Forest#2]

Appears you need to consider a replacement engine.

Several riding mowers used that type engine. (and salvage prices and or running [price would be less than cost of the parts you need.
You need to consider looking for a vertical shaft engine replacement.
I've got couple snapper's, a old Gravely and MTD mowers that use that type engine.