Let me start by saying "I don't get along with Holleys" But for 16 yrs my 65 chevy 292 had an Economiser on it and it was an amazing carburetor. For 8 of those years the truck was sitting and it didn't need rebuilt, just tuned. That carb got me 16+ mpg city and I haven't been able to find a replacement. Maybe I'm so pissed off at the 1 bbl Rochester that the economiser is seeming better than it actually was. If you liked the economiser lineup join me in sending Holley a request via this form: http://www.holley.com/TechService/TechRequest.asp
It seems like Roy Johnson of Johnsons Speed here in Lansing bought a truck load of those things. Can't hurt to give him a call at 517-321-6460. Roy, Steve or Greg can take care of you. They do some mail order and Ebay. Been in business since the mid 60's.
I put one on my wifes 68 Camaro when they came out. It was such a turd she made me put the stock carb back on!