I guess if they look at the MCC then yes they will know about the 734 time, but just don't add by saying something like I have been in the sim all last week preparing
not sure on the speed difference between the 734 and 738 as I have only flown the 738 but it is a quick ship, the assessment wont be done to throw you at it full speed though, they know your not used to operating it so things are spaced out a bit to give you a chance to configure.
Good luck.