I have a '68 that originally came equipped with power drum brakes. When I bought the car there was a set of disc brake rotors, spindles and calipers in the trunk. The calipers are the four piston style which I thought were used only on the '67 Cougar and that Ford switched to the single piston calipers in '68. My car’s build date is Dec 7, 1967. Which calipers are correct for my car? I also noticed that WCCC lists different brake line kits for early and late production '67s. Assuming I go ahead and use these parts and they are from a '67 what is the difference between early and late 67 brakes? Which front brake line kit and hoses should I use, early or late '67? I know I will also need a different proportioning valve but I believe those were the same from '67 to '73 for disc brake cars.
The difference in brake lines comes from the location of the proportioning valve. It is near the rear axle on early cars and up by the distribution block on later cars. You are right that you have '67 or earlier parts. Personally, I would swap them for the '68 parts that would be correct for your car. They are cheaper and more common to find parts for.
Is there any advantage to having four pistons vs one? I realize there are more parts to have something go wrong with but the number of pistons in the caliper seems to be a big deal on newer cars. For example, the 2013 GT500 will now have six piston front calipers up from four on the 2012. My guess is it has to do with more uniform and higher clamping forces. Yeah its kind of an apples to oranges comparison but just wondering why Ford gave up on the Kelsey-Hayes design after '67…
Expense. One piston caliper was cheaper to produce than four. The K/H brakes work great and with the right pads will stop your car faster and more consistently than the single piston.
The single piston floating caliper is correct (and cheaper) for your car.
The down side to the 4 piston is for a car that is inactive for long periods, pistons tend to stick. You can change fluid every two years or use a premium grade of DOT5 synthetic fluid to help with the pistons sticking. The 4 piston setup is expensive, a rebuilt 4 piston caliper is around $120., single piston 68 is around $30.
K/H rotors are the same as 65-66-67 Mustang.