According to the Wix catalog https://www.wixfilters.com/Lookup/FilterBySize.aspx?catid=1&styleid=1 their number 42304 is 3 inches in height and 10 inches in diameter. This number is available at many stores and sites including Amazon, NAPA, and Summit Racing and most parts chains, at prices from $11 up.
I used this site to find a paper filter to replace the copper mesh on my 1940 Super. It is actually for some Briggs & Stratton Tractor engine but
Thanks for the replies. I'll check out the Wix 42304. Regarding ebay, there are many listings for Wix 42080, which doesn't fit my car. I bought one of those filters from Rock Auto and had to return it because it was much to big in diameter.
Had to pull out the old Buick Master Parts Books and Shop Manual to find good data on this filter.
The original filter on your car had a reusable poly foam element which fitted over a metal screen. Should your car still have this type, the element (if in good shape) just needs to be washed in kerosene and reoiled every 8000 miles. The GM part no was 5645166 or AC Delco A96C.
By the early '70s the dealerships were supplying the disposable paper-type element for this car. The GM no was 6420137 or AC Delco A180C and was found on many '60-67 Buick V8s. These numbers cross to Wix 42082, Hastings AF60, and probably others. Typical dims are 3.03" H, 9.96" OD, 8.62" ID. It was also used on some Chevy/GMC trucks and full-size Pontiacs of the era.
I found as you did most suppliers give the wrong number when looking up the filter by car model. The Wix 42080 (or AC Delco A63C, GM 1553695) is much larger and goes on many '58-59 Buicks. I was able to get to the correct filter on RockAuto by looking it up for a '64 Skylark V8. Everything needed from the Wix catalog referenced by tjbian above has been correct. The ID on the Wix 42304 (7.54") will likely be too small for your car.
Std shipping charges from RockAuto look to be about $11. NAPA or other national chains usually have free shipping if the part is shipped to a local store.