Re: Greeting from dynamic downtown Dickinson, Texas
Welcome to the forum, Blank. A China girl will probably fit, if you modify the intake (like they do with the Schwinn banana seat bikes from the 70s). If the seat tube interferes with the carb, you can saw the intake manifold into two pieces and reconnect them with automotive heater hose. You will make it flexible where it can be moved to the side of the seat tube. Plenty of examples on this site.
Bike shops should be more helpful because you will likely purchase parts for your motorized bike from them. There are some mountain bike shops in Phoenix that sell electric and gas assist bikes. They get it and see the potential.
For your first build, I would motorize a steel framed mountain bike or beach cruiser. Installing a motor on these frames will be very straight forward and you will soon be riding and enjoying it.
After you have that motor kit broken-in and you are more familiar with it, you can transplant that kit to a challenging custom bike like the Falcon. Just my 2 cents.
“You're only young once, but you can be immature as long as you like" -Unknown