I'll just preface my remarks by saying I think you're using too much viscosity, (assuming you're not operating at punishingly high operating temps) not in the sense that it would cause harm to the bearings, but in the sense that it's causing parasitic drag, both in driving the pump, and in the rotational forces of the rotating assembly. Probably only amounts to a very small hp loss, but it's there.

That being said, with that high a viscosity at operating temp you could probably support more bearing clearance, although I'm not sure why you'd want to do that. A less viscous oil would likely accomplish a similar result depending on what your objective is.