The quoted height is 60'1" no mention made of bridge clearance so I have always worked on the given figure. I add the height of my VHF antenna and subtract 3" for the amount of junk I carry on board.
Am also terrified every time I go under a bridge despite all my calculations of air draft. In Holland they only lift their bridges just enough to get the tallest yacht under and Hunters are very tall for their size.
Veeery nerve wracking!
If you want the mast length try asking Z Spar.