I pulled a complete hydroboost assembly, all hoses, mounting plate, pedal, pedal bracket, and pushrod from a local u-pick yard for $125. Came off a '82 diesel, and is bolting onto a '87 gas. Paid $50 for a rebuild kit and installed it myself. Don't have the truck running yet, so can't guarantee all is fine, but it should be.
I'll be using the factory brake system other than the booster. I did not pull the pump from the donor, because it had the remote reservoir type, and I doubted that would fit on a LS engine. I don't intend to bother tapping both returns into the pump reservoir. Instead I'll just tee the return lines together. May also install a PS cooler that I got with my LS donor vehicle. If so, the return lines from the hydroboost and the steering box will be teed together before they go to the cooler.
Further, being an 80's truck, my truck uses metric o-ring fittings on the lines. The booster I bought is the same way. The LS power steering pump uses the same fittings. I can buy new high pressure lines for a 80's hydroboost truck, and they should fit perfectly between this mishmash of '82, '87, and 2010. The low pressure lines will need to be fabbed, but that's easy.
Earlier hydroboost units had flare fittings instead of o-rings. Research the year breaks if it matters to you.
Am told that all hydroboost units are the same, other than the fitting type and a few other minor things. Just need to do some more fabrication for the mounting bracket and pushrod, if pulling from a non-squarebody source. Theoretically most Astro vans have hydroboost, and it's supposed to be easy to get it off of them.
Best rebuild instructions that I've found are
here.