You've got a hard pedal, that means the hydraulic portion is working correctly. Bad Calipers or dry rotted brake hoses would make the pedal spongy. You can't rule those things out, since a "Hard" brake pedal can be subjective, so it may be much harder than before, but still soft enought that you could have some caliper/hose problem.
Check the adjustment on the rear drums. If the rear drums are out of adjustment, the brake pedal will take more of a stroke to build pressure (because the all the soft pedal motion is going into extending the shoes to reach the drum surface, only when the shoes hit the drum surface does the pressure in the pedal start to build). Its called pedal height, how high up is the pedal when it starts to build pressure and make the brake bite. Poorly adjusted rear drums will have a "LOW" pedal height, i.e. you have to push the pedal down pretty far before the brake bite and start braking. Well adjusted rear drums will have a "HIGH" pedal height, i.e. you barely have to push the pedal down at all to get the brakes to bite.
As mentioned, the pads and ROTORS can be your problem. Not sure on the pads, drying out? but I'm willing to believe they can detiorate just sitting in the elements, semi-mettalic pads are called that because they have iron in them, could the iron corrode? BUT, I'm willing to bet the ROTORS were all rusted, sure the rust scrapes off as you use the brakes, but what did the rust do to the surface of the rotors, did it pit them? (sometimes the pits can be hard to see) change the hardness of the surface?
Maybe the pads need to "BED-IN" into the surface of the rotor, since it has changed from the rust that accumulated since the two years ago when the pads were last used against the surface. So maybe in a hundred miles or so, maybe the pads will bed in and braking will improved dramatically.
I'd:
1st - Adjust the rear drums, then after driving 50 miles or so with braking, go back and adjust them again, there is probably rust on the inside of the drum as well, and after the rust is scrapped off you'll need to adjust the rear drums again.
2nd - If the braking doesn't improve within a 100 miles of braking or so, enough time for the old pads to BED-IN on the changed rotor surface. I'd go and get the rotors turned and get a new set of quality pads and put them together.