It's easier than it looks to just pull the pump out. Since you're replacing the high-pressure hose just cut it in the middle.
Once the pump is off the engine the hose fittings on the pump and the steering box are much easier to access.
I'd replace the low-pressure power steering return line as well.
Continental manufactures hose that meets SAE J189 & hose that meets SAE J2076 power steering return hose specs. SAE J189 is rated for 100PSI and 250°F. SAE J2076 is rated for 175PSI and 302°F.
SAE J189 should work on regular good old fashioned power steering systems. You can get Continental SAE J189 hose from any CarQuest parts store.
SAE J2076 is what I use on Hydroboost setups and it takes a bit more work to find.
The clamp I can see on the return hose in the first picture looks like a German Fuel Injection Hose Clamp. If you have to replace the clamp get another German Fuel Injection clamp or get some Rotor Clip style constant tension band clamps in the correct size for your return line. The German Fuel Injection and the Rotor Clip type band clamps won't cut into the hose and loosen up like the cheap Ideal Worm clamps that the Borg will try to sell you.
I did a writeup on hoses and clamps and tubing on one of the other GM truck boards...
http://67-72chevytrucks.com/vboard/showthread.php?t=696742