Flexible hydraulic brake line diameter

[47 dodge 1.5 ton]

Needs some help. In effort to “upgrade brakes” or just have good brakes, I need to replace hose from frame to rear axle. 
  I have 5/16” line from master cylinder to rear, now replaced the original 5/16”  OD lines to the banjo with 1/4”OD  copper nickel double flared ends. 
  I am looking for a 1/4” ID hose and tee block for (2) 1/4” OD double flared male ends. Is this something not available? 
 All hoses I have come across are 1/8” DOT flexible lines. Is this correct for trucks(larger B series) Cant imagine going from 5/16”down to 1/8” and back up to 1/4” to the wheel cylinders? The original lines to the wheel cylinders were 5/16” for the rear  and a very large unidentified hose dropping from the frame( ID measures .280”)
  This is the 3rd try at getting something to work as I posted questions around this topic a few months ago. Last ditch effort was replacing the original 5/16” axle lines to 1/4”, use the B series banjo’s use the 1/8” dot flexible line from DCM and use the B series block. This was a failed attempt so far. 
  Another thought was maybe the B series used a heavier return spring than the W series? 
  Starting to get expensive testing out new ideas. Everything in the brake system is Brand New or professionally reconditioned by white post. I still have the very large wheel stepped cylinders on the rear as this was the first thing I targeted and was trying to stay OEM at the time, Maybe they are too large for these undersized lines?(bigger bore size than the 1 1/2 ton B series I have for parts) 

  I have good brakes, I don’t have good  release when letting off peddle, delayed several seconds.

[9 foot box]

   Some information from my W-series parts book. I googled 1193583, and there is one on eBay in Alberta. Rick D.