As I said, IMO the port is already big enough and a 1.5 valve is more than enough area.
Even if I use a 2.05 intake it keeps the seats further apart.
It won't be beating my head against the wall. A big valve on the exhaust hurts power. For years the 1.94 exhaust was standard in BBC stuff. That has been squeezed down to 1.800 on the small side and 1.84 as about standard.
A 1.5 valve a 95-96% bowl is better than a 1.6 valve and a 90-92% bowl and it loses power as the bigger valve and bigger bowl.