Several valid approaches are described in this thread. I think mainly it depends on how original you want it to look. Elsewhere I have seen suggestions to REPLACE a transfer cover with a flat aluminum plate. This I would not do as I can´t believe it wouldn´t mess with the performance of that cylinder.
The pic of the early covers with a boss look as if they are intended to be drilled and tapped for one eighth pipe thread for a remote pump. Possibly this was an early Gale setup…
