I would use the new type that is a 4 hole with the bottom half machined away and flowed.
I Believe they come in 1" or 2 " as in everything else always check for flatness of mounting surface. This is where most baseplate's break.
I'll find the name of it if interested.
Vacuum carbs liike the better siginal it gets from a 4 hole.
Use the 2" if you have the room.