Check the "Chain Adjustment" thread right under this one. There are instructions on how to recenter your brakes while adjusting the chain. As for the chain, if you still have the stock chain on your bike, now would be a good time to replace it. The stock chains are junk. They have a bad habit of breaking up internally, and looking like chain stretch. With the extra load the tight brake put on it, I would imagine it's done for. You didn't mention which bike you have, but get a good chain by Tsubaki, D&D, or other good chain manufacturer. If you have a C5, you cant swap an Oring chain, tight in. If you have a G5 or B5 and want an Oring chain, you need to put an 18 T sprocket in instead of the 17T it comes with. Anyway an Oring chain will work quite well from one of those suppliers.
Give a close look at your sprockets and make sure they are still good. Bad chains can take them out quite quickly, especially the countershaft sprocket.
I put the 18T and Oring chain on my G5 and was very happy with the regearing and result.
Don't expect any great change in performance or mileage. it ain't there. It does move some vibration levels around and give a more pleasant ride.
Bare