confused on these brakes

yeah you will only have a fitting issue if the wheel cylinder length differs.
and i have no idea if they do between 9 and 10 inch.

you may find that some have angled port for brake pipe and some don't.
main thing is that they bolt in and they do not force the shoes out to a diameter bigger than the drum... i.e it won't fit with the adjuster at the minimum.

9 inch brakes perfectly adequate on a car with nothing in the rear provided the fronts work well.

huge brakes on the back mess with the brake bias and suddenly the rear end is locked up when the front is not and you find you are facing the traffic you just went past.

i.e if they worked before in an adequate way i'd just replace with the same.