I run into a lot of older bikes with 52/39 and 14-28
These were usually the lower end bikes, but they provided the wide gear ranges for entry level riders.
However, 42x28 with a 27" wheels gave 40.5 gear inches at the bottom.
39x25 with a 700x23 wheel (and everyone rides 23's since Lance rides 23's) gives 39.4 so you have a slightly lower low with the new gearing.