Fiber optic sight height

Hey guys. Looking for a little insight from y?all. I have a BFR with a 5? barrel. I?m looking to replace the front sight, with a highviz sight. The website doesn?t really give height measurements. I?m figuring that there?s probably someone on here, that?s purchased a replacement sight from Magnum Research. If so, what one would you suggest? I would love the lower of the three blades. But, with such a short sight Aperture, the lower sight might be out of the question. Any suggestions?

Yes,, There is a mathematical formula for figuring the height of the front sight, Dawson Precision has it.... Use it to determine the height.

Thank you!!