Which rear end to use

[Rob Fisher]

I am trying to decide which route to take with the rear differential on my 1964 GMC long box. It has a mild SBC and will have a 700R4 installed soon.
I currently have the stock Dana 44 with plans to completely rebuild with new lower gear ratio and some brand of posi-trac. Also planned would be a rear disc brake conversion using a kit from www.tsmmfg.com which would include Cadillac Eldorado rear calipers with integral park brake. The other option would be to put a truck 12 bolt in, again completely rebuilt and using brackets from CaptainFab and '93-'97 F-body calipers with integral park brake or a Wilwood product with the separate small drum brakes in the hub as the park brake..
The questions that I have are:
1. Which rear end to use, Dana 44 or Truck 12 bolt.
2. Which gear ratio to run. (looking to improve off line performance over
the current 3.07:1 in the truck now).
3. Which is better, calipers with integral park brake or the Wilwood style
with the small drum brakes used for the park brake.
Any help or advice that you can offer is appreciated.
Thank you,