Raised Port Head Question

Well...... if you end up without a radius there...... yes, it will create a stress riser.

For a mild cam situation...... will it matter?

I’d rather try and do it in a way that doesn’t end up without a radius there.

For a no machining option......
A smaller diameter spring might work, or a spring that’ll work at a shorter installed height, and then some -.050” locks to move the retainer away from the valve tip.