roller rockers

[Benz Dr.]

That's actually the hardest part of this idea. I can make ther roller part work but the ball stud is a real challenge.
 Although there's a lot of friction on the ball stud it doesn't wear all that quickly if everything is kept adjusted and maintained. It is however, very prone to barrier lubrication failures due to dirty oil.

[seattle_Jerry]

You can use a metal with self lubricating properties for the problem area. I forget the metal we used for bearings on our injection molding machines...it would end up being a maintenance item...
Or use an aerospace plastic. Research research research.

[TheEngineer]

Drilube! Drilube is the answer. It's a molybdenum-disulfide coating, grey in color. Boeing uses it on all fasteners and other places that may be subject to galling. Talk to your local plating shop.