Same here. Past owner got the length wrong, Rock Auto got the length wrong, vendors don't care to pay attention and then I got smart and realized it was the same pump body and shaft length involved. All I had to do was pull or press the mounting face to the correct distance. I hope the spacer works out.
Steptoe's,
since my problem is not the stock water pump height I'm staring a new topic hopefully to help others with this kind of a problem (and help my patience and sanity) and will paste in your good ideas.. I've painfully learned more - but luckily not *the hard way* so far
https://www.ultimatesubaru.org/forum/topic/185922-shimming-water-pump-pulley-to-align-with-crankshaft-pulley-only-need-3-5-mm/
Thanks
Craig