I've been experimenting with roller rockers made for the 2.6L and 2.8L Ford "Cologne" V6s on a new World Products 2.9L head, though it could be done with any 2.9L head.
I've milled the sides of the stock cast aluminum rocker shaft pedestals to allow the rocker arms to line up better over the valve tips. (I've gone this route because the guy who makes the roller rockers pretty much refuses to make arms for the 2.9L engine because of the increased offset and poor arm-to-valve orientation on the 2.9L. Seeing how bad the alignment is, I can't blame the guy.)
I've replaced the hex head bolts with allen head cap screws to allow the pedestals to be milled enough for the arms to line up over the valves. I'll either have a portion of the allen head cap screws' shanks milled to allow for proper oil routing, or I will further mod the pedestals with an oil distribution groove or two. A small o.d. AN-grade flat washer will be fitted to reduce galling of the pedestal top.
The real test of whether this works will be to see if milling the stock cast pedestals weakens them to the point of failure. I'll build the first engine as a street-going guinea pig. If the milled stock pedestal idea is worthy of just the trash can, I'll have pedestals milled from billet aluminum. My few fellow conspirators in this madness are suggesting that steel pedestals would remove all doubt about integrity, but we'll see if we have to go there.
The accompanying photo might better explain what I am doing. The front assembly has not-ready-for-prime-time pedestals made from billet aluminum. The rear assembly has stock cast Ford pedestals with lots of milling done to the sides. Once I have the pedestals milled so the arms are where I want them I'll have aluminum spacers made to keep the arms in place.