Replacing Manifold/Stove-Pipe Gaskets

Dan- if I upgrade to the 73 manifold as I'm thinking I'll do, and convert to Electronic Choke - would my kit be 1231?

In that post it says: "For all slant-6 applications with 1bbl carb from 1960 through 1972, the kit number is 1231."

I have a 1bbl carb for 72. Why did you recommend 1233? curious