FIrst of all, point me to this furler system you refer to. Love to see what it looks like and what it has to offer.
I have been using Harkens furler
Harken Furler with retriever line guide On the sail itself, you are far better off to have the sail made new. Spinnakers and Hooters are very differently shaped. The performance of the Hooter is far more versatile, however -- it sails upwind, on a reach and down wind.
Downwind you need to heat up the boat a bit more than on a spinnaker as it the leading edge that has all the lift, not the amount of sail and the big shoulder.
Good luck,
Rick