According to Shimano, a Deore FD is made for a 48t max chainring and 22t total difference between biggest and smallest rings. Your intended setup would exceed that so you may have problems with the bottom of the chain rubbing the cage or difficulty shifting.
You also need to check your rear derailleur to make sure it can handle the increased wrap required with the larger biggest ring.
Personally, I would simply coast once I get up to the point of spinning out. At high downhill speeds, you are wasting a lot of energy fighting wind resistance for just a little extra speed.