RE: reversing an engine
I have used two different 45 engines on my Bob Cat running backwards. Rotate the front housing 90 degrees CCW. Works fine but the carb is substantially lower so tuning is different.
I am currently using a 50 engine with pusher props. Tuning is also different because the airflow across the engine is less. Ground run time is limited. I have had a few problems with the engine not coming up to speed on take off.
Bill