Dude, what the hell???
They didn't switch to the H23 in 97. Why would they put a less powerful motor in the newer body style? All 97-01 Preludes have H22s, there was no other motor choice. From 92-96 the Prelude had either an F22 (base model), an H23 (Si model), or an H22 (Si VTEC model).
You've got it completely backwards. The H23 was available from 92-96 and then dropped for the 97-01 generation, not the other way around.
If somebody who works at a Honda dealership told you that then they should be fired; they have no freakin' clue what they're talking about...
Edit: I just noticed your profile says you have a 98 Prelude...how do you not know this???