I was lucky enough to find the little 90-degree bracket shown in Turna's photo. If you can't find one from a '70s/'80s GM car or truck, you might be able to fabricate one. Take some 1/8" or 3/16" plate, cut out a rectangle about 4" x 2", heat and bend a 90 about in the middle. Drill a hole in the corner, about where you see the bolt in the photo, and just keep trimming until it fits. Then push the PS pump up until you can mark a hole where it can be adjusted up or down (mostly up, unless you have a Hulk arm). Finish trim.
Or, find a '90s truck or Camaro serpentine system like LAXrated is advertising. Yes, you will need a reverse-flow water pump and fan and you may have to change out the PS pump to one that fits the bracket. Just need to swap the valve/fitting at the back base - put your '79 valve in there, and you can reuse your hose. But, if you want to keep going, get a new Camaro pump and 12.7:1 800 steering box, and upgrade several things at once. Motor's out, now's a good time except for the cost and delay...
$20 bracket or $500 in parts. Red or blue pill. Your call. ; )