The pump is a standard SAE A 2-bolt mount Sundstrand TK19.2, with a 5/8 keyway shaft, a #12 inlet port, a #6 3gpm priority port, and a #8 6gpm auxiliary port. It rotates counterclockwise, and carries the Surplus Center part # 9-2027D.
I messed around with several different mounting locations and configurations, and the best overall location for mounting the pump came out to be on the right-hand side of the engine, right alongside the starter and ignition coil. Note that my original plan was to mount the pump so that it protruded THROUGH the grille. I decided against this because the plumbing was so much simpler, and the pump wasn't out where the loader bucket could lose something and break the pump loose.
To mount it, I started by taking some parts of an electric clutch (Thanks Keith!) and laying out the engine face's bolt-pattern on a cardboard box. Then I made a rough measurement of the pump shaft's location with respect to the crankshaft. With drafting tools, I located the center of the engine's output shaft...
...then transferred the rest of the measurements to cardboard
...Then did a test check, cut out the holes, placed the pattern ON the engine (using clutch bolts!) for a test fit.
...Then made some 'adjustments' to the final position with razor-knife and a roll of 'anti-gravity'...
...Then I took the data, and my pattern inside, and drew up this scale drawing.
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pumpbracket.pdf
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Tomorrow, I'll stop by the scrapyard for a piece of 0.250" steel plate, and I'll carry along the CAD file and see if I can find a shop that'll laser-cut the plate for a decent price. If not, I'll drill and torch-cut the worst of it, and finish the job with a bandsaw and disc-grinder.