3/4" drive belts

Mini Bike & Go-Kart Parts

I'm assuming these "kelvar" belts are a new thing (Kelvar 1958??) What did they use previously.. Just a regular V belt? Reason being... I've got (basically) a 20 set-up, but my "shaft to shaft" is 15" Longest "comet type" belt I can find is 12-13" or so. Rather than going to a whole new drive unit (I see a 40, 7/8 belt with a belt that will fit), which I really can't afford.... Shouldn't a standard V belt work? (yes, I know I'll be changing it on occasion, but its an easy belt change). Will this work?
Sounds good.... but I'm as far back as I can go (and the jackshaft is as far forward) All I can think of is maybe the original engine crankshaft was higher up in the engine block (and thats a long way up.. just can't see it)... all I can go is DOWN, so.... looks like(maybe) I can mount the jackshaft on the UNDERSIDE of the frame and gain at least a couple of inchs... be easier to lengthen the chain connecting the two jackshafts... OK.. going to make a couple of blocks, notch the frame & see where I end up... tnx