Welcome from California!
Please post pics when you can.
I am especially intrested in your Hawthorne.
Here's mine: http://motorbicycling.com/f15/pictur...rne-10546.html
As for your throttle issue, if you are good with fabricating cables, try a minibike throttle. At least they are made out of metal. Though you will need to come up with a different kill switch.