My bad its been a long time since I've hot-rodded a G54B, can't remember half the stuff I once knew about em.
Looking at the stock 12 Valve head it could probably be done. The bore spacing is close to the 225 /6 and the bolt pattern looks similar.
I'd attempt it, but I don't have any /6's anymore and I only have 1 extra 2.6 head. Cleaned out and scrapped the rest.
