I will be installing a 66 circuit Square D NF 277/480 panelboard soon. Have not seen it yet but the enclosure is 86" high. Will need to watch out to make sure highest breakers are not too high. Not too concerned about having more than 42 poles because the nature of the connected loads will not have anymore circuits loaded at same time than I would be able to put into a 42 circuit panel. I will be using 54 poles in my installation.