Foward and reverse gearboxes

Lawnmower gearboxes are good for home made single seat cars. Then there is the gearboxes from outboard motor legs that are forward and reverse and are about 110 degrees from square and are robust enough to put say ten horse power threw the box. The one I have comes from fifteen hp mercury. Using the outboard leg you can use a vertical shaft engine from a mower. This is a series and I will advise you as to what parts to look for and how to modify them.