A third 212cc engine is made for your go-kart and doesn't advertise itself as 6.5 hp like the other two. User reviews note it could reach 11.8 hp, so it seems you'll get some kick out of it.

The truck's owner decided to fix his problematic Ford with what is effectively a go-kart engine, one with just 6.5 horsepower. Somehow that's actually enough to move this old truck.