PRE 15 - Exporting Blu-Ray @60fps

I've searched the forums extensively, and I am beginning to think I am not phrasing the search terms right, because someone has to have had this question before.

I have v15 and I'm trying to export a blu-ray @283052 with a custom menu.  My source material is 720p60, so I'm fine with the blu-ray being 720p, but the only output options I see are 1440x1080 and 1920x1080, both of which limit me to 29.97 fps.

Is there a way to export at 60fps (or 59.94?).  I have found options for exporting to "custom" but I do not believe this is going to output a blu-ray iso image for me to burn and play on a player.