I think the general consensus is that Glulx, given the right settings, can handle games of any size you can think of, provided your computer can handle it. I know that a few people here are working on absolutely huge projects, with thousands of objects and rooms. I have seen an almost text-only game currently being developed where the final file was 30MB or something like that. So you shouldn’t worry too much about it, I think!
Performance may end up becoming an issue, though. If you find your game to be running too slow, Zarf recently gave some tricks to potentially make your game faster.
Getting slightly off-topic here, I can’t help but think that if someone made 2 games that would work off the same savefile and change behavior depending on what’s in the file, that would be super cool 
I don’t really know how it would work, though.