Engine Z425 John Deere twin cyl. 22 hp b/s

Thought I had posted earlier, however, the second 22 hp JD briggs stratton engine has throwed craps in a matter of 4 years on a Z425. Is there an engine that will interchange besides the B/S that anyone has tried, like a kohler, kawasaki or anything besides a B/S?

Thanks for any input,

goat roper