Best budget disc brake rear or disc conversion???

[Z11WEAVER]

Helping a buddy on a converted 72 4wd converted to 2wd Blazer. Purchased factory trailing arms flip kit, 6" drop springs, adjustable trailing arm crossmember for a total of a 8" static drop in the rear to include a weld on adjutable panhard bar. He currently has a decent 75 5 lug 12 bolt 3.73 c10 rear that was contemplating on converting to disc. We cant find an affordable kit or just the correct caliper mounting brackets alone to do the conversion using astro van brakes. What rearend choices do you all recommend that can be used that are budget oriented and are preferably narrower than the 75 truck rear, that come loaded with factory disc brakes? A 5.3/4l60e is being used. Not looking to race, but want good reliability. Thanks in advance.