O Ring inner deck area

I picked up some old BAE fuel heads. The 2.40 intake valve is extremely close to the O ring in the head. On a few cylinders there is basically no deck material on the inside of the O ring area near the valve. I need to move the O Ring out to fit the Larger 4.505 cylinder. I'm hoping to deck them and carve a new place for the O ring out about .044. That would only leave about .022 of deck material near the intake valve. Will that be enough to keep a seal?

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