Roller Rockers For The 12 Valve V6???

[Duk]

Has anybody seen, heard of, or smelt of roller rockers for the 12 valve v6 engines?
I noticed the other day, a very oily exhaust port in my engine. The spark plug doesn't show any signs of excess oil going through the combustion chamber, so I am thinking its got stuffed valve stem seals and probably valve guides.
A previous owner of the car had some work done and that included 'Fully overhauled heads'. Now that can obviously mean anything and may not have included new valve guides. Either way, these engines are prone to valve guide wear and that primarily comes from side loading the valves when they are working.
Any other suggestions for long term durable valve guides with our 12 valve engines?
IAP sell manganese bronze guides and they claim they out last the original guides, but has anybody used them and can attest to their long term durability?
Teflon valve stem seals?

[Duk]

Rather than start another thread I figured I'd just add to this 1.
After giving the idea of making some roller rockers some serious thought, I put that idea aside.
Instead, I figured I would try and add a small spray bar inside each head head to aim a squirt of oil to the valve tip/rocker contact area. The Nissan SR20 engine uses a very similar approach with its valve train.
Ideally the squirt would be pointed downwards so that there is as much opportunity to squirt oil at the contact area when the valve is in motion rather than just when it's parked at the top. Actually coming up with a way to get the high pressure oil in there will be a challenge. I figured I would make a spray bar that is fed via a fitting that passes through the camshaft cover (sealed either side). That fitting would be fed via a fitting Tee'd into the oil pressure sensor's gallery.
Mounting the spray bar could be fun  .
The easiest way would be to have mounting lugs/tags that sit over the head studs/under the head nuts. I'm not overly keen on that because it could (probably wouldn't, tho) cause inconsistent head nut torque results. That, and the twisting force when torquing the head nuts may twist the mounting points and snap them off the spray bar.
Another way would have the main spray bar mounted via camshaft cap studs and use long individual tubes that then go over to the exhaust valves. The potential problem there is that the long tubes would be unsupported and would more than likely vibrate. So they could potentially crack and fall off inside the head.