Re: Need help with some direction.
Let me start by saying Welcome to the forum. Next you will get plenty of advice from the members of this forum. In my opinion I would suggest you stay with the 80cc. motor as that is what I have I also weigh in at around 300 lbs. and it moves me down the road just fine. Now as far as the bike I used a Huffy Mountain bike from Wal-Mart due to my needs and my budget Both were the same as yours as well. I found the only change I really felt I had to make was the seat, handlebars, and Tires. the knobby tires really give a rough ride. The handlebars keep me from feeling I am leaning/hunched over and the seat is self explanatory. I spent a couple hours looking over the different posts here and found some very useful information. The thing I learned that was the most affective "Locktite" use it! Really it makes a huge difference. You will get plenty more advice from the folks that helped me, listen to them they know what they are talking about. OH by the way these are addicting...It starts out as a need and before you know it your wanting to build another one just better than the last one with better paint,wheels,exhaust,custom tank and so on. Good luck.
Once again welcome to the forum.
Hope it Helps. I am also a proud member of the 20 MPH. club