Sure - we've yakked about this before. After I eat dinner I'll take some measurements and tell you what will work. Personally, I would just machine duplicate threads and turn a hollow threaded cap, but I understand about not having an engine lathe. What I'll see if doable is to tap for a common SAE or metric bolt size - since you have a drill press you could partially drill out (hollow) a cot-off bolt.

Another thing you can do with your drill press is to chuck up a scrap of aluminum rod and "turn" it with a file - slow and careful - until it fits. Cut-off while chucked and spinning with a hacksaw, epoxy in the end, cross drill and pin so it's secure against shear, and file/sand smooth and radiused on the outside after epoxy sets up. You'll need to keep your file card handy as the aluminum will pin (clog) the file quickly - if you load the teeth with chalk first it's not as hard to card the aluminum out of the teeth.

Dinner shout just came down - I'll post dimensions later tonight.

Tom