A couple of people have mentioned that 753 is "superlight" and that's a reason not to ream...
All frames with a 1-1/8" seattube and 27.2 seatpost have about the same wall thickness and thus about the same weight - there in the seat tube anyway, not talking about total frame weight. So the main difference between a 753 frame with a 27.2 seatpost and a 531 or Col. SL frame with a 27.2 seatpost is that the 753 frame is stronger there, as long as the framebuilder didn't overheat it and lose the heat treatment. 753 is lighter elsewhere in the frame, but there where you're reaming, it's not lighter, just stronger.
Jack told me privately that he has a first-gen two-bolt Super Record post in 27.2 that he'd like to use, and that is such a lust-worthy post that I'd ream that frame in a heartbeat to be able to use it. To lathe-turn that post would be criminal!
Mark Bulgier
Seattle, Wa
USA