Just out of pure curiosity: why would you want any Windows based on the NT structure for your retro rig? Many games of those days just refuse to run on Windows NT. Why not go Windows 98 instead?
I will admit, I have never actually used Windows NT 4.0. The first computer I got was in 1999 and it had Windows 98 on it. To date, I think 98 is still the best Windows Microsoft ever released (twice). I agree that I might be somewhat biased here due to the nostalgia factor but from what I've read, a lot of people would agree with me on that.
Windows 98 is compatible with the vast majority of 90s and early 2000s games. It also has a really good DoS support, which makes it even better. I was a total noob back when I got my first PC. In fact, the first time I've actually used a computer was the day it got delivered. I had no idea that there is such a thing as a compatibility problem and I sure as heck didn't know how to deal with one. (In fact, at the time, I thought opening more than three windows was overheating the monitor. And yes, I was one of those idiots who though the computer is in the display itself. I was 7, though.)
The important thing is: I never had a compatibility problem those days. Not once. Every single thing I installed on that PC just worked. Zero problems.
I'm sure by now you see my point. Again, I'm just curious.