I missed this first time around, so this is a new thread so far as I'm concerned. I'm fond of the old Schwinn straight bar frames that most of us refer to as "panthers" whether they were that model or not. Mine is a 1950, runs a 99cc Predator engine through an EZ transmission and does low thirties with the big rear sprocket I'm running. My bike has a canoe sidecar so I needed to gear it down some to handle the additional weight and drag.
You're going to love your panther as a motor bike. I very much like what you did with your seat and the resulting position and look it gives the bike. I wouldn't worry about how long the build takes. Besides, once you ride yours for a few years you may be ready for a re-do. My sweet panther is beginning to look like it has been fighting with other panthers... some rust showing here and there, scratches and dings. And as I know more mechanically than I did before I think next time around it may get a different engine and drive system, more like the old whizzers. I'm playing with a 147cc 2 stroke Jacobsen and belt drive to a sheave on the rear wheel on a 51 Schwinn cantilever frame and if it works out as well as I hope then the panther may get the same treatment. Someday. If I live long enough.
Keep your photos coming and don't worry about how long it takes. Thanks for sharing your build!
SB