Swap that bike for one that will accommodate the engine. It will save you bunches of money. You can always paint your new bike the color you want. Chances are , you can find a cruiser a color you like. I do like the tires though.
you would have to cut off the top tube that spans the steering to the seat post and then weld in a similar sized tube that is straight in order for there to be enough room for the engine.
2 strokes take a lot of mechanical skill/knowledge to maintenance and modify.
I would recommend you get an expensive electric setup since there is no maintenance to an electric bike other than changing the batteries once a year.