Now you're talking. That is a Honda XL70 frame. The swingarm, forks, and wheels from an XR125 will bolt right up, if you want full size wheels. The frame will handle 80 mph. It will not accept the HF V-twin engine, but a much better engine will bolt right in: a Piranha 140
. The 140 is designed for motorcycles, has a built in clutch and transmission, and has enough power to both accelerate well and maintain highway speeds. It is also quite a bit cheaper than the Predator V-twin: a little over $400 including shipping.
The XL70 is street legal, and the seller of that frame is offering a bill of sale. So if you ever decide to register it, you could do so. If your home state is too stringent, Vermont would be happy to register it and send you a tag. No title necessary because Vermont doesn't require a title for motorcycles under 300cc or over 15 years old. This frame qualifies on both counts.
How do I know so much about this bike? Because I built one, and ride it regularly:
You could also build it as a chopper, as in this picture
. This one is an SL70, which is pretty much the same bike with a different name.