So I got curious....
I think there's a number of bad things that could happen. My gut feel is that it's probably not going to be a happy thing to treat a 3.3v part as a 5v part.
If you can't find something similar that's 5v (Remember, if you want a 32k ROM and can only find a 64k one, you can always just ground the topmost address pin and not worry overmuch about it) there's actually a proper process to swap stuff over.
A nice, technical piece is at
http://focus.ti.com/docs/logic/catalog/resources/appnoteabstract.jhtml?familyId=279&abstractName=scea035a. I don't understand half of it myself, but it looks like what you want to do is to have a 5v -> 3.3v and 3.3v -> 5v level translator. There's more stuff at
http://www.fairchildsemi.com/an/AN/AN-314.pdf
A 74HCTxx or 74ACTxx buffer will accept 3.3v outputs and convert them to 5v. I'm getting the vauge impression that some buffers may be "overvoltage-tollerant" devices where they can handle 5v on the input... I'm thinking you want a 74AHCxx device. So an 74HCT244 or 74HCT244 to go from 5v down to 3.3v, and a 74AHC244 to bring it back up to 5v.
Remember to take the propigation delay of the two buffers into account to make sure you can still drive it at the proper clock rate.