Hey as long as you like it who cares what your engine wants?
The 6.4L GenIII this thread is about probably had an 18 psi cap at the low end, might have been 21 psi. Even a 12 psi cap still puts the boiling temp of plain water at 242°F. And if you're running a 50/50 with antifreeze its more like 259° (16psi 50/50 would be 267°).
Regardless, nothing it going to be hurt running that engine at 200°F, absolutely nothing. It will probably run BETTER.
