Good looking build. Since you asked, here are a few ideas for your consideration:
- Add a front brake. I have a similar bike and the coaster has worked well for me, but at speed it can be slow to stop you and there are many horror stories when they fail. A front caliper brake is cheap insurance.
- As previously mentioned, be sure to fortify the front fender. Having a ski for a front wheel if that thing comes loose and spins around is not a good day.
- Spend extra time making sure the drive sprocket<-->chain<-->rear wheel sprocket are perfectly aligned. Saves all kinds of problems later.
- When you are done with the everything else, shorten up those cables. Easy to do with a dremel cuttoff wheel.