I'm sure your 40 is simmilar to my 46 so you can use a master cylinder from a 69 mustang (drums front & rear), fab up a bracket that will bolt to the original holes in your pedal assembly and replumb your break lines. It's a little bit of work but if I can do it. It can't be that hard.

You'll want to make sure that your brake shoes are good and that your brake cilinders are in good condition also.

If you want some pictures of what I did contact me directly and I can e-mail them to you. (Sorry I can't post them here)

George