The brakes sounds to complicated. Not in terms on parts but in terms of getting it to proportion properly.
I've never done this with a truck axle but with proper trailer axles, you can buy assembled brakes. Like everything on the backing plate, including the backing plate, shoes, magnets, springs and 1 wire ready to go for like $100. The wire up a brake controller in the truck and run 1 brake wire to the trailer light connector.
Well, as of right now this is a drum brake axle. If you're familiar with old vehicles in general that were drum/drum systems there never was a true proportioning valve in the sense that, say, our gbodies with drum/disc systems had. Just werent all that necessary. To the extent any of the old drum/drum vehicles had anything at all it acted more as an idiot light actuator to warn a line pressure was down, and was less about acting as a true 'prop valve'...
So, if I keep it as it is, I'd probably go with a basic surge brake actuator, probably with a reverse lockout, and keep to the 4 pin wiring harness. The KISS principle. The truck weighs in at the 8600 lbs so using the federal regs it's going to far exceed the 57.14% ratio for surge brakes to be legal as it also is under 12000 lbs. Heck, fully loaded its going to be under 4 or 5000 lbs. I don't see putting more than 2-3X00 pounds into a bed floor that is 8'6" long and just over 4' between the tubs. Or, just over 6 feet between the sides.
As an aside, the fed regs make you scratch your heads sometimes because if the trailer weighed 11999 I'd be at 71.6%... but at 12001 I'd fail the test as the ratio jumps up to 80 reqd ratio. And for a non-commerical vehicle its about as heavy as they get. With what most people probably move surge brake trailers with the gap would get much larger. But that's life by the numbers. It's also how uhaul gets away with surge brake controllers on its auto transports for example.
BUT, there is an interesting wrinkle in the whole project creep angle. I've contemplated pulling a disc brake axle from a 2500 series gmt400 platform to share service parts with the yukon then selling this one. In that case it would become a disc brake setup, and I'd be looking at an electric hydraulic actuator, a 7 pin wiring harness, and down the rabbit hole we go with extra parts, and ballooning costs... surge costs 40% or so of electric hydraulic before you get into axle swap costs and such. Of course, it would be nice to someday get this thing done, so I need to keep that in mind.
For now I may default into getting busy with other things before welding up this mess. The cab floor is still bolted to the frame too. I left that much of it in place to help keep the frame horns somewhat aligned for when the cross bracing gets welded in further rearward than the cuts begin for tapering inwards, although, I suppose all that really matters is that everything checks out as level right before burning things in at the end. Plan there is to level the tops of 2 pair of jack stands to each other L-R, FRT-RR doesnt matter as the frame has vertical dips, lower rails onto the stands, then make sure the tips are still level at the apex where they'll meet. That part will be much better QC than redneck trailer number 1 which pulls straight surprisingly but probably shouldn't.
