You certainly CAN convert the hub to the Mustang stile bearing retainer set up with the cotter pin and forget about worrying that the retaining nut is going to loosen up on you.
For what you are going to do with your car you should probalby consider that?
I already did it, but that was quite a while ago and don't remember specifically the bearing numbers but I seem to think everything was straight 65-69 Mustang components.
The hubs and rotors will even bolt up. The issue in using the 67-68 Shelby Trans-Am big Ford-Thunderbird brake calipers was simply the differences in the caliper bolt center lines.
The Pantera uses the typical European 3" center to center and the US uses a 5" center to center bolt pattern.
So as you probably had discovered you need an "adapter".
While I am thinking of this, there are also a few aluminum 4 piston "Thunderbird" calipers and "replicas" around that are relatively reasonably price, the Girlings even in iron are ridiculously expensive since you are actually sourcing them from other limited production makes like Aston Martins.
You won't find any aluminum versions of the iron brakes that exist or were ever made by Girling. Not in 4 piston calipers you won't.
There are a few US Panteras that were raced here back in the day that have the Shelby Mustang Trans Am brake set ups adapted to them.
The ONLY drawback I can think of with converting to the 65-69 Shelby Mustang Trans Am front is that with the development of wider profile racing tires, the front spindle on the hub suddenly became inadequate.
Ford fixed this by increasing the outside diameter of the spindle on the 69-1/2 hub and put into production on the 70 Mustang Boss 302 and about the second half production of the 69-70 Shelbys.
That pretty much fixed the spindle failure rate.
The front Pantera dimension are engineering copies of the 65 Mustang, translated into metric dimensions and given to European engineers to modify those into production parts, whether actually using existing production parts like the wheel bearings or sourcing components out of local suppliers.
To my knowledge, the Pantera race cars never got the same upgrade to the spindle dimensions that the Mustangs did and what I find unusual is that virtually all of the Pantera race teams had no idea of the relationship between the Mustang and the Pantera.
Their reaction to it to me is, WTF are you talking about jerk-o? This is a Detomaso, not a Ford Mustang? Really? Makes me wonder who the jerk-o really is...and I don't think it's me but then again, a real jerk-o would never realize what's really going on around them right? LOL!