AAM 11.50 rear disk brake question

[76chevycummins]

Hi I've been following this site for awhile and finally decided to join up.
I have a question I'm hoping somebody can help me with. I'm putting together a 76 chevy k 30 crew cab with a 12 valve cummins. I'm to the point where i'm ready to put in a rear end (truck was a dually when i got it). I picked up an AAM 11.50 axle for it awhile back but I'm unsure what I would need to do to make the disk brakes work with the existing brake system. I have searched around and there seems to be a lot of different opinions. New master cylinder, modify the proportion valve, or put in a pressure limiting valve. The thing is I need the brakes to work properly because the truck will be used to pull a lot of weight from time to time. I'm also considering just going with a 14 bolt with the drum brakes on it. this gives me the assurance that the brake system will work as GM designed it to. I've never had a problem with the rear drums on any of my other trucks stopping me so this idea appeals to me a lot, but it would require setting the 14 bolt up with 3.73 gears. Anyway I'd appreciate any help or opinions. ps sorry if this has been covered before.