front axel swap

[wanted]

I recently bought a 70 gmc 3/4ton 4x4. This is my first experience with this this era of trucks.
It has a stock front axel with drum brakes and no power boost. I want to add disk brakes and power. I am assuming I can swap in another front axel with disks on it. I found a yard near here that has a 3/4 ton gm axel with 4.11 gears and disks but I don't know the year. My question what years will directly swap into my truck with no modification? Also, I know I need a proportioning valve for disks but would I also need larger diameter brake lines?
Any info on this swap would be appreciated.

thanks