The standard Magic 8-ball reply to this kind of query seems to be something along the lines of:
"Every historical SJG book-like product that is NOT a licenced product will see an e23 resurrection at some point. Other details hazy!" :-)
See here. eg.:
http://forums.sjgames.com/showpost.p...63&postcount=3
This is a GURPS-specific answer, though, and the titles you mention might not be covered due to some detail I have no insigt into ;-)