An LSA of 106.67 on a 10-1 ratio on an 5.9 Magnum headed engine would be the technical math on one equation. But don’t do this. I would be inclined to move it down a degree or two on a low compression engine to help generate air movement.
The Hughes cam is designed with timing events to help increase the cylinder pressure. It’s all in how the cam is ground and Hughes went out of their way to do this.
I also went looking for my flow sheets of the OEM Magnum head. I couldn’t find them. But I can tell you what I remember from them and that is the heads flow peaks at .500 and the air flow doesn’t really increase much.
It actually dips and makes a come back the higher you lift the valve. We went to extremes on valve lift. .600+. A lift you’ll never use and probably can’t use with the stock pistons.
Lifting the valve higher past what the grind is already cut for isn’t much help at all. While I’m sure there would be a lower increase, it wouldn’t be a big thing.