The calipers aren't particularly heavy but the rotors are.
I think the differences in weight between the stock calipers and T-bird is 5 v 7.
The rotors, that's a different story, but you have doubled the mass.
In both of my installations, the rotors are installed in the stock locations, behind the hubs. The '68 just has more shims between the hub and the rotor then normally.
Wheels. In my case, I went through a set of calipers, grinding them down too much and they holed through looking for clearance for an original 67 Shelby 15x7 Ten spoke wheel.
What I wound up with in the front were a pair of the current "repro's" from Branda which really look identical to the originals but are machined on the inside of the wheel to give maximum clearance.
With that wheel, a kissed edge of the caliper and a1/8" spacer, I just clear.
The Pantera is much less problematic since it looks like Campagnolo had brake clearance consideration built into the wheels from the beginning.
The only short commings on the Pantera swap is there is no "big spindle" for them and the caliper mounting to the upright is only an M12.
Sorry I can't remember the name of the SoCal "Classic Brake Company" (maybe that's it?) that had made up a batch in aluminum.
In that thread that you reference someone here seemed to be familiar with them and said the castings were not exactly the same and had at least one addition flange cast in which might or might not interfere with the entire concept of the swap.
When I inquired with the brake company they admitted they had made them but withdrew them for concern of casting porosity and the market was too small to be worth correcting the issues for them.
As I said about caliper weights, when I did an "engineering review" upon completion, I just didn't see significant value in pressing for aluminum calipers especially considering the original Ford design is a "thin casting design" to begin with and changing from iron to aluminum would be reducing the strength of the caliper and considering the stresses the caliper COULD be put under risking failure, it wasn't worth additional effort to go that way, unless of course the aluminum calipers just happened to fall into my lap.
Funny you should mention mounting the hat over or behind the hub. Current thinking, especially in a scenario where it would be advantageous to have a quick change assembly, mounting the rotor over the hub would be a superior approach in my view.
As a matter of fact, that is exactly what we are going through now with the rear of the Pantera.
We've run into just a little bit of a snag with this concept of doing it on a KK idea of finding something already made in large quantity and applying it just like this big brake scenario for the T/A cars way back when.
However, these silly I - Talians insisted on machining the od of the hubs to 5.9". The proximity of the center line of the lug studs to the edge of the flange apparently bothered them a bit and they put an addition bit on meat on the outsides.
The Pantera flanges do not seem to be a hard steel forging. They look more like a softer cast iron alloy so there may have been some engineering consideration in providing more meat for the lug studs?
So that kind of eliminates using something with a hat id made to sit over a Mustang hub and puts us into the relhm of custom made. Not the way to go. But I'm still working on that.
Incidentally, I went with a Lincoln Versailles rear axle with discs and a parking brake.
The Pantera in the rear so far is the stock solid rotor with a Tesla EPM and 67 Mustang front discs.
The 65 Mustang front rotor does fit the rear of the Pantera (as well as the front) but all of a sudden became a one piece with hub. Go figure?
So the brake set up on my GT350 RESEMBLES the T/A cars and my Pantera RESEMBLES the factory Group 4 brakes. Porterfield R4S pads all around.