Drivetrain swap HELP

[NewType72]

Alright I'll get right into it I need some advice on my current daily driver/long haul road trip vehicle (currently short trip)

First off I'll give the run down of what I currently have

72 C/10 2WD SWB

1: 350 SBC motor old block 60 over on it's last leg only produces maybe 280 HP
2: 350 Turbo Tranny freshly rebuilt with a shift kit very solid
3: 12 bolt short dog leggin rear end with ring and pinion howlin like a banshee

Secondly What I forsee in my final buildof this truck

1: 350/350HP ZZ4 or built long block I have (not concerned until next spring on swapping my old motor for this idea

2: 700R4 overdrive tranny with shift kit and high end innards (I will find a shell from a local auto parts graveyard from a late 80's-90's truck and have my shop completely gut it and rebuild it with new parts

3: Ford 9" rear end with posi and disc brakes (I have my eyes on a complete housing with axles and gearing and disc for about 200$ from a friend of mine have also heard that they may have made extr short versions of these and that they were 5x5 bolt pattern and this is supposedly it) If so I would swap out my old 12 bolt for this and get the correct freeway gearing and be on my way

4: Salvage my 12 bolt and put in a Eaton or Powertrax Posi with correct highway gearing and freshen up the whole setup and save the disc brake conversion for a later date

NOW here's the big question what am I better off doing ((money not an issue just time to make it I wanna do this right the first time)) and what is the better setup for what I want to have?? also what will I need to change to accomodate for the longer 700r4 moving the old crossmember out and replacing it with a tubular one from a company and also buying a new driveshaft to fit the setup? I plan to do just the tranny and rear end at this point so I can have those dialed in before a put in a fresh motor..

would be very appreciative of ANY helpful advice or pointing in a direction of a build on doing this swap thank you all