Slant 6 Roller Rocker Arm Vendor(s)

I believe the Cox Bros. were a machine shop, one of the Brothers passed away IIRC unfortunately, I do not believe The shop is fabricating them any longer. PP&R and another Aussie outfit offer them as well as at least one of the big domestics(T&D?), read big $$$$, usually ~ $1,200 a set or higher. I've not heard any opinion on the Unlimited's......