Aye, as Giantcfr1 said above, you could potentially swap out the cassette for one with different gearing on the 7.4, and you could also put slightly wider tires on the 7.5 (not entirely sure of how much wider, but it depends on the clearance). These would indeed be questions best asked of your local dealer, as each shop will have different deals on aftermarket parts/accessories with bikes, and that sort of thing. That being said, if you're used to wider tires, then narrower ones might just take a bit of getting used to (it took me a little while to get used to my first road bike, partly for that reason). I hope it works out for you, in any case.