Normally I'd advise reading up on how to reinforce the fenders. You being a beginner builder it'd probably be best to remove the fenders completely. You need a second brake since the bike only has a rear coaster brake. Last of all the bike frame is aluminum which many builders prefer to stay away from. If the bike is still under warranty take it back and get something like a Road Master mountian bike. I'm currently building a Schwinn Sidewinder featuring a triple chainring shift kit.
Maybe a Roadmaster Granite Peak would be better. It has a steel frame, brakes,
and a 68 inch wheel base. On the engine kit, I would go with the 80c Zeda 80
triple 40 from Bicycle-engines.com.
I don't get all the worries about using an aluminum frame? I have done many aluminum framed bikes over almost two decades now and they all are still working fine, I have two of my own that are aluminum and they have served me well! All the tank frames are aluminum and other than people breaking the front pedestal mount which I believe is from improper mounting they also seem to last just fine.
Manufacturers make aluminum frames thicker to help compensate for aluminum's less tensile strength. But steel you can weld it easily, its not as rigid, and it has a fatigue limit.
I don't get all the worries about using an aluminum frame? I have done many aluminum framed bikes over almost two decades now and they all are still working fine, I have two of my own that are aluminum and they have served me well! All the tank frames are aluminum and other than people breaking the front pedestal mount which I believe is from improper mounting they also seem to last just fine.