That's a good question. I'll say that I usually use posi seals on the intake and umbrellas on the ehaust for exactly the reason you describe- I don't want any chance of starving the exh guide for oil. It's a combo that has worked well for me. Most oil consumption seems to happen on the intake side anyway since it's under vacuum all the time from the intake port, unlike the exhaust.
However, most aftermarket heads come with posi seals on both intake and exhaust and I don't hear many people complaining about worn out exhaust guides because of it.
LT-1 heads I'm not sure about. I think they have posi seals on both intake and exhaust but remember that the factory can make minute changes to the seals and whatnot that might not be obvious to the naked eye. |