Hello,
What is an MT? The answer is to buy a straight style carb V-stack and slip a rubber hose over it with a hose clamp. connect the other end to the air filter of your choice. If a MT is large, you could us a good size from a motorcycle application or something to get low restriction and good filtration. Engine selection depends on your power needs. If you need a clutch, many trimmer engines will have that.

Dave