Would Ga Tech be a good fit?
GT will not be invited. The most obvious reason is to understand why the SEC has already looked at Texas A&M and perhaps Missouri. It is all about TV markets those schools would bring to the SEC, and the TV money that would result from SEC's future contracts with its TV partners (CBS, ESPN, etc). A&M brings the Houston and Dallas DMAs (DMA = measure of TV market size) to the SEC, while Mizzou brings St. Louis and perhaps Kansas City DMAs.
But the Atlanta DMA is already delivered to the SEC, mostly via UGA and AU and to some extent Bama, UT, UF, etc. Atlanta is already SEC country, so GT isn't needed.
The bottom line is that any new SEC school will have to be accretive to the SEC's revenues in order to be considered. That means the revenues that the new school brings to the SEC will have to be greater than the slice of the SEC's earnings pie that they get in return. This will be the driving consideration, even though it is a given that other factors will be considered to a lesser extent (tradition, lack of probation, cultural and academic fit, existing grudges from other SEC schools, etc).
Finally, just to put the final nail in GT as a SEC candidate, a previous post referenced that GT already left the SEC once. True, and that will indeed be held against them.