No I'm not sure that would be safe to assume. I also have a 95 Kilauea that surely has the same seat tube as the 94 Kilauea, and yet the 95 doesn't want the 27.2 but the 94 likes it. I think a 27.0 will be ok for any of these frames, but in cases where the man with the reamer had to do a fraction more reaming, maybe a 27.2 becomes feasible (and therefore better).
The post that's in there now is a 27.0 and I suggest you go by that - if it is very loose (e.g., falls down the tube under gravity) or has to be super-clamped to hold it, then probably a 27.2 would fit. If the 27.0 feels not too bad, likely a 27.2 would be too tight. Or you could ask the LBS to try a 27.2 on it when they do the service, just to see.
A suspension seatpost is definitely standard advice for back sufferers, but I should declare an interest here - if you were to put that O-Beam on eBay I would be a bidder!