The one year only 1970 disc brake master cylinder for non-hemi E bodies has a casting number 2229171 and has a 1" bore. The drum brake master cylinder is 1" bore also, however the pistons are not the same as the disc so the kit cannot be used for a disc brake master cylinder. Some of the seals can be removed from the kit pistons and used on the disc brake pistons, but I don't think that kit has every seal needed to redo both disc brake pistons.
The 1-1/8" kit they list for a hemi will not work on the correct 2229191 casting number master cylinder found on '70-71 disc brake hemi cars. The primary piston is too short. I know this first hand. I had to have some pistons made up several years ago to restore one of these master cylinders I had at the time.
I used to work for the company that made United brake parts, I know very well what there catalog lists and that there are many errors.
I don't believe any kit was ever manufactured by the aftermarket to service the 2229171 casting number master cylinder, even in the 70's. If anyone did list it back then, it would have been an OEM Bendix kit purchased by an aftermarket company and sold in the aftermarket companies box. Good luck finding one now!