Not sure how I got here many months later, but I'm doing a Hydroboost swap in my 65 modified car and this car came with factory disc brakes. As it turns out my brake pedal might have swapped as it has the drum brake pedal.
But really, his whole topic is about pedal ratio.
Take the center to center distance of the pivot to center of brake pad (in side view) and divide that by the distance from the center of the pivot to the center of the pin.
A non-power car (generally speaking) should have a pedal ratio in the 6:1 area. Power brakes are in the 4-4.5 area.
[Naturally there is a correlation to master cylinder diameter, not discussed here.]
Using the data from my drum brake pedal I get a ratio of approx 6.5:1. Very standard for a non-power car.
If I increase the distance by 0.25 the ratio is now 5.3:1, hence the pedal pressure is higher (if the same master diameter and calipers are used).
Interestingly the 65/6 power brake system uses the same drum brake pedal and the ratio is changed to 4.3 by a ratio changing bellcrank before the booster.
The 67/8 system changes the pedal ratio by mounting the pivot higher in the pedal box and moving the pin appropriately. So yes, the pedals are very different.
In the case of a Hydroboost system on a 65/6 you have to get down to the boosted pedal ratio in the 4.3 area, so you have to move the location of the pin on the pedal even further than either pedal since there is no bellcrank. Not that any concours person would do something like modifying a 65
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