seizing brakes and possible z32 brake conversion

[minianthunter]

well I've been working on my 240 for awhile now and i need some advice about the brakes

All 4 of them are pretty crappy i just replaced the pads on the front ones and they are working alot better than before but mechanics that have looked at my back ones have said that they are seizing? which i am lead to believe is that they are able to push down but the mounting bracket is crap and it isn't able to give a little bit of leeway so they stop applying pressure to the rotors.

Anyways what im getting at is, is there any cheap fix for this or am i going to need to get new calipers and mounting brackets/aftermarket stuff or can the seizing be fixed with some new mounting brackets, if my above assumption is correct.

If i do need to replace them i have been looking around for prices on new stock parts and its gonna be in the 150s range, but if im gonna be spending that much on stock i might as well try to get some aftermarket ones, at least i know they will be better for the buck.

As for the z32 brake conversion would it be more difficult than putting in new stock brakes? is there anything i need to worry about with compatibility, like rotor sizes? and if i were to go through with the conversion would it be wise to only do the back ones or should i do all 4?

sorry if its lengthy and if i wasn't specific enough let me know and ill fill you in to the best of my knowledge.