you dont need a kit to do the conversion, just a few bits of kit. start with the 67 drum/drum master cylinder. next you are going to need some brake line. you can get it already setup with fittings and flares from most parts stores, they will be straight though so you need to bend them up yourself, easy enough to do, in fact if you are careful you dont even need a tubing bender. i didnt when i did this conversion on my 64 falcon.
you will also need a "T" fitting that you can use to mount the stop light switch. i think its a 3/8" pipe fitting, but it has been a while since i did this conversion. you will also need fittings to screw into the "T" that have the proper SAE fitting for teh brake line, that will also screw into the "T" fitting.. you may also need adapter fittings for the master cylinder as well, i did. you dont need teh distribution block though, or a proportioning valve either if you stick with the drums all around. you will also need a couple of plugs. the stock distribution block has three outlets you only two of them for the front brakes, so plug the third one. also you need a proper coupler to splice the rear brake line to the one that comes from the master cylinder. again a straight through fitting with the proper adapters like you use on the "T" fitting will do nicely.
take your time a measure the length of lines you will need, and dont forget to add a few inches to each line to allow for bends.
one more suggestion, when you are buying these bits, step up and buy the wheel cylinders from a V8 mustang and install them on your stang. this will upgrade you wheel cylinders, and actually give you some improved braking due to the large wheel cylinders. nit a great deal, but it is noticeable, at least it was on my falcon. the nice thing is that teh wheel cylinders bolt in place of the stock six cylinder ones.