Did some reading and there's a reason they don't make them.
Not enough demand. You can have one made at a local machine shop
specifically to fit your outboard. High performance/speed/propeller shops
will be able to give you more information.
The problem with add on nose-cones is that over time
they've been known to separate from the gearcase.
Not something I'd want to happen at speed.
The real speed demons install high performance lower units.
Nose cone and low water pickup are part of the housing.