Watch some videos and learn how to rebuild the drums, its not hard. Do one side, keep the other intact for reference, take pictures along the way.
Even with the elusive Eldorado calipers (which are expensive, very hard to find rebuild kits for, and generally suck, as stated) I really have not been able to consistently hold an e brake setting, and I can usually drive right through the applied e-brake. Pretty sure I would fail the Texas state inspection on that, nevermind the other stuff that is "wrong" on my K5.
You will also spend a huge amount of time just doing the conversion, in addition to the cost (not as cheap as it used to be).
If you are dead set on going disc, go disc, it will stop better once you work out all the bugs (Brake master, Prop valve, ebrake cables, bleeding and re-adjusting the calipers, and bleeding again....)
If you need to re-gear at all, just go find a newer style axle (e-brake in rotor hat, 2005?+) and adapt that whole axle to your truck (move spring and shock mounts)