The Oliver parts book shows it pointing down, and that's the way it is on the majority of my Olivers, including our 2-44 fork lift which I know has never been messed with.

They originally came with a spin-on filter, part number 100 126ASA, which is still a good number. Ag Parts First now has a real nice filter chart in PDF format that gives filter numbers for popular Oliver filters. They also have another that gives the carburetor numbers for the different models. Visit <!-- m --><a class="postlink" href="http://www.agpartsfirst.com/Oliver_home.html">http://www.agpartsfirst.com/Oliver_home.html</a><!-- m --> for both charts.

Another handy site is the Wix filter look-up. If you have a Wix number, someone should be able to cross-reference it at just about any auto parts store.
<!-- m --><a class="postlink" href="http://www.wixfilters.com/filterlookup/index.asp">http://www.wixfilters.com/filterlookup/index.asp</a><!-- m -->