Originally Posted by
modelmartin
It does not take much to lock up the rear wheel. That will occur long before it bends the frame! The fork could conceivably need gusseting and I will likely add that right away.
I WILL be building this bike. I have a picture in my mind of what I want. I am a machinist and have worked in automation and fabrication. I can make it work. I don't care about what is practical, pragmatic or efficient in this case. I will assemble and test the bike before I paint it and if it needs more support I will add it. I also am NOT going to buy a new bike. Anyone with money can do that! I want a unique, beautiful and stylish bike and the pride that comes from building it. It's a rando bike after all. It is not a racebike or mountain bike. Besides it has a pretty weak motor!

Oh boy...weak motor has nothing to do with it when you have some giddy-up from a good hill. It's your bones though.
You could get a steel fork that can accept a disc brake.
Good luck aligning the brake mounts on your frame and fork. Nil margin for error there. Avid has a technique and a jig for aligning the brakes themselves on an already designed as disc frame...I strongly suggest you reference that and other info akin to it.
A few other notes. Put a spare set of pads in yer bike kit.
Get a rotor truing tool.
Read everything you can on how to properly set the brakes up. Most of the numbnuts who whine about brake squeal, shuddering, etc.. do not know a damned thing about how to align the calipers on the mounts, and how to properly set up the brakes. Pay attention to what pad materials are for what application. I use sintered metal pads, supposedly the ones that are the most susceptible to noise, and because I know how to easily maintain them I have no issues...