How much spring pressure is too much?

I recently spoke to Lunati over the phone about one of their cams (10200705, the big Voodoo for a small block) and the set of Comp 987-16 valve springs I got as a gift.

With the 1.6 rockers I have on my Edelbrock heads and at a 1.800" installed height, the pressures work out to be 120 lbs closed and, on the exhaust, right at 340 lbs open @ .590" lift. I would expect that the pressures will be lower after it's all broken-in.

The Lunati tech said that was on the upper limits of what the recommend on hydraulic lifters, with their cap being 350 lbs, but he didn't think there would be a problem running it. He also strongly advised that I run a high zinc oil, which I was planning on doing.

Is this too much pressure for a street/strip engine? What would be a safe limit? Anyone run pressures this high on a street/strip flat tappet hydraulic? How did it hold up?