How can I get this to work?

So I’m running this 212cc engine in a kids quad and I need to have it face this way because of the exhaust and that I will need a jack shaft to run power to the axle. I wanna know how I can do this to where it won’t run the wheels backwards if there’s a way. I thought about using gears but i don’t have the sweets clue how to do that and also know what gear ratio I’ll have. Please shoot me any ideas you might have I’m willing to try a lot lol.