Brake problems

I think my master cylinder is going south or the bootster either one. The pedal fades horribly and I have to pump them alot of the time to stop all the way. I dont think I have air in my lines but I will bleed the brakes just incase.
Anyways I have seen in magizines about how people use the master cylinder out of an integra to swap into their CRX or civic of some type. They usually do this after they swap in bigger brakes. Would it be worth it to do it with stock brakes or would it make a difference?

an 89 integra brake master cylinder is a direct bolt on and it wouldnt hurt your braking performance, your pedal travel would be less and you will have to get used to it because i assume that you will lock up your brakes if you apply the same pressure that you used when you were using your Si M/C

went to the junkyard and got a master cylinder off of a 91 CRX si. That seems to have fixed the brake fade problem. The brake fluid in my car was a nice black color. I mean it was completely black as is could not see through it at all. I flushed all of that out and added new fluid. All seems to be good now.
I am hopefully going to be putting new rotors and shit on my car after I replace right front upper control arm (ball joint is dead)

the bad fluid may have deteriorated a seal in the mc.