RHS heads with 1.44" O.D. valvespring?

I have RHS heads from Hughes with their 1110 springs - not sure the OD but I used PRW stainless 1.6 ratio and had to machine a bit off the underside to clear. They are quite hard , buyt easily done with carbide tooling. I used a ball endmill so so it would blend with a radius not a sharp edge -no spot for stress fracture to start