Keep this MC???

[firehawk408]

I have a 73 firebird with C5 frt. brakes and 80 trans am WS6 rear disc brakes. I have a master cylinder from a 80 trans am WS6. I used this master with the rear disc brakes and stock 2nd gen disc brakes. It seemed to work okay. Since swapping over to the C5 brakes I haven't driven the car again. Started a long restore process. From the research I've done a 1 1/8 MC is recommended for this setup and I believe that is what this MC is. My question is, before I could even get my car running with the new brakes I notcied this leak where the MC meets the Booster, should I repair this leak and continue on or replace the MC all and all because it is not correct for this combo? Thanks for the help, I know this "finding the right MC" question has been beaten to death but I just couldn't come up with an answer doing a search.