Please tell me where I said I did not swap out the spindles.
That is implied when doing this swap because you cannot fit calipers to drum brake backing plates.
For the sake of skuzzy, I guess I should mention the specs. and measurements of every single bolt, cotter pin, pinion depth, brake stroke length, until a simple post mentioning a relatively easy upgrade becomes bloated to the point of being unreadable.
BTW.............I just performed a very similar upgrade to my 1967 fastback with 428 cobra lemans engine and top loader.
You're barking up the wrong tree of a resource that could help you greatly on your cobra kit since I have experience with factory 5, superperformance, 260 cobras, 298 cobras, 428 police interceptor cobras...etc....and build the fastest cars in the world for the people who can afford them.
My employers have been billing customers $160+ per hour for my services and have been since 2009.
Not a brag......just an indication as to where I am concerning skill level.