That set of 308's were just made wrong.
No rockers had the correct contact pattern..... Not even stock ones.

I'm sure the poster above with the 576's that have the tops of valves all messed up has a set of heads with a similar problem, but maybe just to a lesser degree.

If the OP sent his heads to B3, I'm sure he'd be able to make some stands and supply a set of rockers that would work.

They could do it at T&D as well, although the price for them to do it may not be all that friendly.