Starting with a stock bike is a great idea. I have done several builds that way. The advantages are you get a HD title. Cheaper insurance usually. The Nighttrain is a good start if you like the blacked out look most of the work is done there.
This bike is a stocker with a custom front fender and black spoke wheels. Its an older model so only a 150 rear tyre. The newer bikes come with a 200.
On the pic you posted the forwards might be stockers just powdercoated black with aftermarket pegs. The fender kit is definitely Heartland. They offer a fender kit to put a 200 on the older models.
This was built from a 2004 Softail Springer. Its hard to build in the reliability of a stock HD in a custom. Even a with a pumped up engine the stocker is typically much more reliable than most scratch built bikes.
This was a stock Softail before we got a hold of it
This was built from scratch but most of the parts came from a Nighttrain that a customer had us chrome out. The frame was a Kraftech 38 degree rake 0 and 0. It was a small tyre bike but still one of my favorute bikes I built. My brother rode it to Mrytle Beach SC before we sold it and it was a nice scooter.