OK, that's better.
The fact that you are 100 lb.s(we are all jealous)means that you can build a decent trail bike for reasonable.
Mind you, it will not climb like a gas dirt bike, but you should be able to go most anywhere.
You will need a larger geared motor and I would recommend this one;
http://www.elifebike.com/peng/iview.asp?KeyID=dtpic-2013-9M-C45T.9DMVU
It's a CST which means you can mount your cassette gears.
The 201 wind. On 48V it should top out around 20 mph. I listed the motor only, because you will need to build a custom wheel that is strong and wide enough that mount a 2.5 inch knobby(Tires, wheels and flats will be your biggest problems).
Other things you will need to think about are battery mounting and torque arms, which can be bike model dependent.
Post or link us a pic of your bike and the rear drop-outs when you can.
I'm guessing you will have to spend around $600 to $800 to build a good reliable trail bike.
If you are still interested, we can cover more of the details.
And go ahead and start reading, it's fun!