Thanks for your input Mustang5L5, in your experience with the fox mustang's brake swap what caliper's front/rear sere you using?
I'm running SN95 Cobra brakes on my '88. 13" 2-piston front brakes, rear single piston 12" brakes. Using a 1" bore MC. My calipers are smaller than yours however.
KTga67, i'd love to help you here, but please take this advice with a grain of salt. I'm very experienced with brake retrofits on the Fox mustang, but it may not correlate on the classic stangs due to booster size, pedal geometry, etc...so please take this under advisement with what you decide to do.
So here's a post i had written for Fox swaps a while back. If you read through it, you'll see where some of the math i'm about to do comes from. Basically what I am doing is taking known 1979+ Mustang caliper setups F&R and comparing them to known master cylinder sizes from same cars.
The Ultimate 4-lug/5-lug Brake Conversion/upgrade Thread
Digging around online, the Kelsey-Hayes front pistons are 41mm x 4 pistons, and the explorer setup is a single 48mm piston.
That works out to a caliper piston surface area of:
4-piston Kelsey-Hayes caliper (41mm piston x 4) = 10,552 mm^2 for both fronts combined
Rear explorer caliper (48mm piston x 1) = 3616 mm^2 for both rears combined
Thats 14,168 mm^2 of total slave cylinder area which is a LOT. If you see where i talk about ratios on that post, most of the factory setups from late models (with similar pedal geometry) are in the 13:1-17:1. Your current setup would be 27:1 with the 1" bore MC. Using the largest MC i list on that page, it gets you down to 22:1. Reducing power assist, or changing pedal geometry can change this however, which is why i say some of this may not correlate.
Let me see if i can guess what your brakes feel like. The stroke is long, and in the beginning the brakes don't respond much. But, near the middle or bottom of the stroke, there will be a point where the brakes grab in an "all or nothing" sort of point. The actual distance from starting to grab to locking up will be short.
I'm not sure i can personally recommend parts here as I don't have experience with the classic. But if anything i've said helps to educate you on making a good decision, then at least I can do that.