Pretty good bet they are the same/compatible size; see here. If you want to be absolutely certain, buy a flange gasket for an Autolite 1100 and a flange gasket for a(ny) Slant-6 1bbl carb and hold them up side-by-each, as they say in parts of maritime Canada.
If you wind up doing this, please lettuce know how it works out for you. Perhaps this time Holley will have put out a retrofit TBI system worth messing with. Dog knows they've certainly had enough tries…!