If I get it right, the weight of the axle will be balanced from left to right. Counting the 'drive hub' as weight on one side is part of the equation, as is tension on the drive sprocket from the chain. The holes I cut in the floor of the chassis are wide enough to adjust slightly. Thinking about it now as I write, it may have been easier to do this on a bench prior to mounting everything, but I'm not that patient I guess.
In any case this pic shows what the stuff looks like without the engine in the way. -CW