I haven't been able to make a trip to the shop to drill and tap a hole yet, but I think that there is enough aluminum to have a secure place for an adjustment screw. It would be a screw that is the same size as the tapped hole already in the pedestal - the curved slot in the distributor is pretty large, so I wouldn't have enough aluminum to secure a screw that big.
My car has a pedestal just like the one that you used in the photos in your post (points ignition, with a shorter tab for the adjustment screw and a large tab for the degree mark....) but it is a five-hour-drive away from me right now, so I just picked up another pedestal while I was in Las Vegas for a school trip. Electronic ignition pedestals were all that I could find!
I'll post up some pictures after I get a chance to do the machining.