As for options it comes down to this; stock "base" gauges, stock rallye gauges, Dakota Digital RTX, HDX, or VHX. or something custom. I have used the stock rallye gauges for years and still have a set in my 70 Challenger RT. When I built my Cuda I wanted something "different" but this was before DD came out with theirs. My first attempt was to use Auto Meter gauges, I was going to use the 5" speedo and tach and 2 1/16 gauges for temp, oil, volts and fuel.
I made a bezel and proceeded to fit it to the dash frame, around that time I discovered Speedhut and changed directions completely. I ended up using 4 Speedhut gauges; speedo, tach and then 2 5" gauges (each with 2 gauges inside them). This allowed me to make a support plate and then use a factory bezel so it looks somewhat factory. It was a lot of work as each gauge is it a slightly different angle.
Around this time DD came out with their first E body gauge set and a buddy of mine ordered one for his 73 Cuda. He lives in AUS so he had them shipped here and i got to really look at them. His set was custom made as he didn't like the font on the original set (the VHX design). He loves them but I have to say I really like the Speedhut gauges as well. If I were doing another custom E body I would probably opt for the RTX set bc they look like the original rallye design.
As to the wiring, obviously the stock gauges need a stock harness or one similar however anything aftermarket can be wiring into whatever harness you have. I believe that the DD set comes with its own harness bc it has its own controller.
What to do with depends on what you want and how much you want to spend.