A recent article in the MGB driver by Charles Durning on a low cost front vented disk brakes for the MGB. I contacted Charles and he shared all the files and more detail with me. I stored all the files on my google drive. Here is the link.
https://drive.google.com/drive/folders/1T-BLFYAAutofikXMnOijZBVEnVduFONz?usp=drive_link
He also did a nice rear disc brake upgrade for his MGB
Similar to the popular Cressida rotors and Toyota 4x4 caliper conversion for Triumph TR4-6. Don Watson also had a rear disc conversion. I think Calvin used it on his TR6 too