How is the easiest way to make a two cycle run the oppositeway, with out having to use a lot of gears ?

If you want to use the engine as in a pusher configuration you don't need to do this, just buy a pusher prop. Else you need to buy a brand that the manufacture has an available reverse crank. Or an engine with a bolt on front housing that you can turn 90 degrees to chang the rotary valve timing.

Sport Pilot thank you for the info on the engines