Stick with the F3 and De-2. It has one of the biggest viewfinders Nikon has made, and the biggest when it comes to Nikon's pro slr's. You won't get any better in professional range.
I recommend getting a B screen. Focusing aids won't probably help with 1.2. Get a screen with no red dot. Red dot screens are usually (my E screen is not though, altough the frame might have been swapped like is the case with my B screen) newer laser matte screens which result in inaccurate focus with fast lenses. Buy a screen where there is no red dot in the frame of the focusing screen.
When viewing image through viewfinder, turn the camera towards some point light source, like lamps etc. and defocus the image. With older ground glass screens you are supposed to see smooth circular shapes. With laser matte screens you see rainbow-colored triangular/hexagonal shapes which look clearly artifical.
Old traditional ground glass screens provide a bright and clear image with fast 1.4 (and faster) lenses. The image gets progressively grainier and darker starting from f2, noticeable at 2.8 and at f4 you really wish you had faster glass. With laser cut screens there is no apparent grainy effect on the viewfinder image with slow glass, and the image is generally brighter with slow glass. But that won't help at all if you have a 1.2 lens 🙂
