I believe you would more that likely have to bleed them. It is very easy to do.

I finally fiexed my problem with the gold platted master cylinder.

I found one off a 90 Cadilac. I installed the entire unit. When I did the brake peddle was only inches from the floor. Therefore, I had to manufacture a brake rod extension to bring the peddle to the right height. What a pain in the but!!!! I hope this master cylinder will hold out.

I know I would have to bleed at least one line but would I have to bleed the whole system?

I can bleed one wheel in just a few mintues but Bleeding the whole system will take a good bit longer by myself. It would take much much longer if I have to bleed the master cylinder.