Been a while since I checked out your build. It's a top notch build. There's a lot to be said for taking a car completely apart and starting with a clean slate. Looks like it'll be a definite award winner when it's done.
I have the QTP cutouts on my Dart 'vert and love them. I mounted the toggle switch where the cigarette lighter "dummy" plug was under the console ashtray cover.
As far as a locknut on the oil pressure T, doesn't look like you have enough room for a locknut and still get the pipe threads to seal. But, front what I see from the rest of your build I'm sure you'll get it right.