Machine off area where lug is so its flush
Drill a hole where lug is and thread it
machine a new lug with a female thread on the back to match tapped hole in plate
screw new lug into brake plate. Use Loctite if you wish
then fit a half nut and wave or spring lock washer to female thread of lug on inside of plate. Just use what ever you have room for so the nut doesnt foul with shoes.
You can also pin the the lug with a little dowl next to the female thread if you make the lug so it has room for one and if you think it might still spin/turn.
Then you can build up the area where the lug meets the plate with body filler so it looks all smooth and rounded and just like its been cast.
Re-paint with black paint of our choice.
Many old english bikes use a screw in brake cable lug that screws into the plate and is retained by a thin half nut and a lock washer of some sort on the inside on the plate behind the shoes.
I have a broken lug on a TLS RM plate and this is how i planned to fix it.
And this shows it roughly fitted and how you can fill in the area around it with body filler or fibreglass resin or whatever to build it up and blend the 2 togther to make it look like its all original.
