Ok, I don't know your exact situation. But mine was having a HOLLEY carb!! Maybe somewhere there is a Shaker base made for this (if someone knows ??).
Anyway mine was very crudley altered to fit the carb. And sucking in allot of unfiltered air and what ever else! I went to an "oldschool" boneyard about an hour from here. And picked up a few fdfferent carb bases. As my yard is "latemodel" so I don't have this stuff laying around any more.
Grabbed 2 mopar and one GM as the airhorn ring is the same size rochester Q-bog to Holley. We used trial and allot of errors but ended up using (dare I tell you) the GM base and grafted it into the exisiting base. We used a ball from a very large ball bearing to press dimples into the base to allow space for the float adjusters on the carb. Although it turned out ok, my final measurements were just a tab off so my shaker is slightly lower on the left side. I hope to remedy this one day. Anyway my pics should give you a pretty good idea.