if you still use the truck for work (i.e. hauling big loads), i'd recommend tracking down some better drums with a little less wear. not an easy task but safer if you're bringing a big load to a stop.
if you're using it just as transportation, you could probably get by with cleaning them up a little and putting new shoes on.
one thing i found when i was working on the rear brakes on my 50 3/4 ton was that i couldn't find a shop that would even clean up my existing drums because they were out of spec. liability issues for them so they wouldn't take the responsibility.
look for a bone yard in your area and see if they have any less worn drums. i had to go through about a dozen drums and pick the best two. most 3/4 tons were really used for work trucks so they seem to have taken more abuse than 1/2 tons.
good luck and i hope you find some good ones!
