I have been looking at the spec line on the mgb gt (68-74) in the ITCS, and several things jump out at me.

1) in the last few years, the GT came with the same HIF carbs as the roadster.
2) 18V series engines (introduced in 72) had a 9.0 CR
3) non 18V engines only had an Intake valve dia of 39.8mm
4) 1st gear ratio wasn't 3.64 in the 68-74 timeframe.
5) Where do I find the non-optional 5th gear?

I guess it hasn't really mattered, because no one has been stupid/insane enough to even LOOK at that spec line..... yet.