Just bring your M/C to your nearest Ace Hardware....They can fix you up with the brass plugs that you need.
They varry with the Master cylinder, You can also go to your local auto parts store and look for their weatherhead bins they have all the correct adapters and plugs there.I have installed a front disk,rear drum, non-power brake kit on my 55. No plugs came with the kit for the unused ports on the master cylinder. What size plugs or bolts fit the front and rear ports? Should I use copper washers on the bolts and teflon sealing tape on the threads?.... Thanks