Couple things: Take really good care of those ball bearings for the front. They are expensive and there is no practical way of converting to rollers. Spend extra on good grease.
Second those adjuster pinions have been available within the past ten years. I believe I got mine from Jim Carter. I brazed the disc onto the shaft and used some phenolic of some sort to shield the spring from the heat. Has worked well for 10 years and counting. When you take the shoes to be relined (I had mine done at a place that specializes in heavy truck stuff) take the drums with you and have the shoes arced to the diameter of the drums. They can also put paper shims behind the shoes to increase the diameter. Tell them DO NOT TURN OR GRIND THE DRUMS. There are no more left, that anyone is willing to talk about anyway. Mine seldom need to be adjusted even though I run in mountainous country, mostly loaded.
I believe those return springs are also available from Jim Carter. If not he will probably know where to get them.
The front's are another story. They do too much of the work and my front drums are getting thin. They are already over the limit and I can tell when they get hot. I changed wheels for ones with bigger holes for air circulation, which has helped some. Still, disc brakes are in my future.
