Mine is to figure out a way to fit a cranckcase breather pipe to the plunger without removing the engine/gearbox, thinking along the lines of limbo dancing with dental mirrors
Should of course have been done when rebuilding, but took advice from a certain well known engineering firm who told me a 60yr engine wouldn't be oil tight anyway.
Well actually it is, except of course for the oil coming out of the hole for the breather pipe, which is then free to run all over the place rather than just dripping on the drive. On the bright side at least that silencer won't rust & don't need to grease centre stand pivot bolts!
While I ponder this I have instead started my winter project, a star twin engine in a '47 rigid frame & hit problems already
, fun fun,fun and it's only autumn