[ERA Chas]

Crash,
You have an early ERA and you state 'XKE calipers' so that's the inboard set-up, not the newer ERA rear.
First off, if there is a Wilwood application and parts for that app, Bob at ERA would know and help you so call him first.
I doubt there is as the fuel tank location makes Wilwoods problematic. Rotors and brackets from Wilwood would put the caliper against the tank. The Girlings are mounted at the leading edge of the calipers so ERA put the tank where they did.
Mike Bontoft who has closed his business (Concours West Industries) created a ventilated rotor and a bridge for my caliper halves which was very effective and fit the stock location. He last posted here about a year ago.
He has machined a set of rotors for the current owner of my car as spares.
Do a search by threads / post for him here and you may get his last contact info.