Rear or front mounted calipers! Whats the difference???

The stock KH calipers for the SBP brakes should be mounted to the rear. From the '70 service manual
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You can swap the spindles side-for-side which would put them on the front, there's no issues doing that with the spindles and it changes nothing except the position of the caliper. But then you'd have to get longer brake hoses and check the sway bar clearance.

The later 73+ disks put the calipers to the front, so if you've done a 73+ swap for the larger bolt pattern the factory put them to the front. But, on a 67-72 car with the stock sway bar and sway bar tab locations the front mounted brakes interfere with the bar. So they need to be rear mounted like the 67-72 calipers were and not front mounted like the 73+ calipers were. Unless you don't have a sway bar, or are willing to make some minor modifications to make sure the calipers clear.

And like the article said, make sure the bleeders on your calipers are at the top. If they aren't, you have the caliper on the wrong side of the car.