you know you can use stock gaskets with a o-ringed block....just got to be careful that,
1. the o-ring is just large enough to be on the outside of the factory wire compression ring on the gasket.
2. o-ring height and gasket thickness should be a matched set to optimize sealing.
3. carefully align the gaskets under assembly.
but dont get me wrong, do this to a EJ and have much better results....and if i had an EJ257 laying around... i would have never been concerned with what can and cant be done to an EA engine...hehe