1970 GMC - Disc brake conversion recommendations?

[HD2000]

I'm considering knocking the dust (and other crap)_ off of my 1970 GMC project truck and getting back to wrenching on it (haven't turned the key in probably 8 years).
I've always wanted to swap out the front drum brakes so kicking around the thought of ordering a kit.
My criteria though... I'd like to be able to retain my 6 bolt 15" Rally wheels.
Any recommendations or reasons to go with (for example) CPP vs POL vs Brothers...
Most of the vendor web sites say "may not work with factory wheels" - any recommendations on how to determining (before ordering) if the kit will work with my wheels?
Also - currently running 4 wheel drums with vacuum assist - I assume my existing booster is fine - just need a new master cylinder and prop valve?