Yes, that's generally how it works. Alta has one for their triple and they added the conveyor belt to an existing lift. Most fixed grips can actually go faster than they do...it's just resorts run them slower for loading and unloading...and with this feature they can speed up an existing fixed grip lift. That said there might be some other modifications that might be needed.
And as to the wind question: all lifts are vulnerable especially with cross-winds. Just look at how often the GMF is closed at JPR. Bonnie is somewhat sheltered (below the ridge) and the top of it just barely sits in the crest. So add some windfencing at the top of the lift and that would help instead of installing a new lift with a terminal higher up and more exposed.
I'm unclear on where the new lift terminates. It's running up Powerline, right?
So does it terminate right at the top of that, kind of IN northway, or cross over Northway and terminate opposite the JFK entrance? I think that would make more sense, right? Give easier access to all aspects.