I was faced with the same issue about 5 years ago. I collected up all the mechanical linkage from a 63-66 truck, cleaned and painted everything and set to doing the install. The undoing of the project was not finding a way to accurately locate the attaching bracket for the frame mounted bellcrank pivot ball. The 60-61 frame is not as tall as the later style, which must be accounted for, but the biggest problem is that I don't weld, and a bolt on solution didn't present itself. If you are determined to switch to mechanical linkage, make sure you have good pictures of an original installation, preferably with a tape measure in the photo showing dimensions, and also note where the push rod goes through the floor of the firewall.
An alternate reasonably priced solution is shown at the attached link. What I did was install a Girling master cylinder on the passenger side of the booster on a homemade plate with a heim joint and spacers. It's a bunch cheaper than a kit and in my opinion works better. Good luck, M.
http://sixty7ss.proboards.com/index.cgi?action=display&board=engine&thread=666
