I'd go with the EMD, but you will have to scrap the airbox. The EMD looks to have an integral supercharger, so just go to VatoZone and get a K&N riceboy cone for it. Rearsets will fit, but not the battery needed to turn that things starter. With the compression ratio, I wouldn't want to kickstart that #$%*!!! So, I would look for the old 60's Briggs and Stratton crank starter. Us older types remember this thing, it's a crank on the top of the engine instead of a pull cord. You wind it up, set the choke and throttle, then fold the crank handle back down, releasing spring tension and starting the lawnmower. Go with premix, and for that custom touch, use fuel scent as it's a two stroke. "Gonzo Grape" is a favorite, for obvious reasons.
It is also available in coconut, cotton candy, cherry,bubblegum,rootbeer, orange, banana,blueberry, vanilla, strawberry, and cinnamon.
Good luck with that!