/6 to V8 Swap Help

I have grown tired of hunting down basic parts and performance parts for a /6. After talking to a member on here (RustyRatRod) I have decided to just do a swap for a 318 or a 360 for the ease of finding parts and for the wider selection of performance upgrades. The other member helped me out with some info already but I still have some questions and I wanted to ask for some help and advice from the more experienced builders of the group. I will add more questions as I hit road blocks.

1) I will have to swap my current 904 for a small block 904. I want to keep it as a push button set up though. Can you guys help me out by naming some mopars that had the V8 push button 904.

2) Which route would you recommend for the wiring? I was thinking of just getting a universal wiring harness so I would be upgraded to the new style of fuses, and because I am going to add other options later like door poppers, electric windows, etc.

3) Will I need to switch out my rear end to a 8 3/4 instead to hold up to a 318 or 360?