Hey Kev, I was thinking about your distributor leak last night as I rebuilt my distributor. Question for ya, have you ever had yours out of the engine? Reason I ask is that there is a small piece of oil soaked felt inside the housing that is used to keep oil from migrating up out of the engine and into the distributor housing. Mine was only about half as big as it should have been and I'm sure it was causing a leak after 40 years. Greg Benders website has a full tutorial on how to rebuild your distributor, maybe that would be worth looking into...
If you can't fix it with a hammer, you've got an electrical problem!