You will want to run the long edition of the PF-24 if you have clearance, which you should have. Came stock on my dad's 66 Catalina. Think the Napa/Wix number is #.51049
I've been using the NAPA version of the Wix 51049 for years on non-Buick engines. NAPA drops the "5", so their number is 1049. As long as you have clearance for the filter, you'll be fine with it. It's a popular number--fits select Olds, Pontiac, Studebaker, International, Buick, Cadillac, and some farm equipment. If I had more time, I'd verify that it has the proper anti-drainback valve, and I'd look to see if there's a built-in bypass valve. Buick shouldn't need the bypass as there's one in the filter adapter, but anti-drainback would be nice.
