will front seats from a 2000 integra fit into a 1990 integra without changing the rails? will the rails off a 2000 integra fit into the 1990?
no and no.
id start with the right brackets for the seats and then figure out how to connect them to the seats.
2 bolts will line up and every time you turn you will lean hahha
falls out of the car into the street like badnews bears hahaha 
buy some sliders and get the wepon r rails and bolt it up and you should be good or you can spend your time and modd the hell outta them to make them fit