Help with first build.

I need help deciding if I need to purchase a new bicycle for the engine kit I want to purchase, or if I need to purchase a different one.
I have a vintage Trac beach cruiser. Its frame is shaped as a Ladies/female bike: as to say the framework that sits closest to my groin is parallel with the lower frame leading from the front of the bike down to the crank. Unlike a traditional male bike that has its higher framework running more level straight across from the handle bar to the seat.
I have searched the internet of pictures of motorized bikes and have not found one ladies bike with the motor in between your legs. I only see them mounted on the rear of the bike.
Is this because of the lady frame? That it can not be mounted at such an angle?

Please help,
Thaks

Well I have decided to purchase a new bike with the new build. Im going out tomorrow morning to find a suitable bike, most likely a cruiser type schwinn or huffy.
Thanks. Ill post pictures of the chosen bike and post them.