Very cool! As I'm sure you'll hear, n frames are somewhat rare and desirable in the u.s., but they are pretty cheap to ship so that opens up possibilities. This forum used to be more active but with the advent of Facebook it has died down, still the best info is found in here but for something like trying to buy a rare frame from a national audience, try posted to lovers of puch FB group, then come back here and start a build thread!
Also, if nobody has told you yet, Texas has the worst more laws in the US, you need a motorcycle license, registration, license plate, and insurance. The good news is that after doing all that you can ride as fast as you possibly want. I rode past cops all the time doing 60 plus and they never flinched. I think since they don't have a moped designation, cops don't really care, and you pretty much have to go 60 to ride anywhere safely in Texas. If you want to build something wild, go balls out!