I think it's best to run the tin shields with the o-ring seals. Doesn't matter with wiper style seals or the old umbrellas but you really need to keep the oil off the stems with the factory style rubber rings.
This is what I'm thinking, given I used this head on my old engine , albeit with smaller intake valves., I will make a Chevy style tool and fit the shields and a set o rings in a few weeks , too much work on at the mo