it's not a trick question
03 R are 43mm and are fully adjustable. are they taller maybe?
they might be a tad longer they have 4.7 in of travel vs. 4.3 for the 919.
that aside i would say(just a guess) that the calibers would also have to come from a R, along with the front wheel and axle.you'd also need to know the centerline spacing(width) of the forks as on the R.
example= say the R fork c/l is 10 in and the 919 is 9 inches the forks would be squeezed by the triples then spread by the R axle/spacers/wheel.
the spacing between the caliber/rotor/caliber mounting point would have to match without rubbing axially and radially.
from what i understand, the f4i is a straight bolt-on all you need is the forks and the fender.
please don't let me deter you from looking into the R6 option farther, i'm all for interesting swaps.
'04 Honda 919, Candy apple red met., 17/44t sprockets,f-16 windscreen,delkevic ss exhaust,Tharbars,givi engine bars, billet alum. led turns w/ running lights,red adj.levers from china, bar end mirrors,grip heaters,adj. foot peg brackets,adj. bar risers,dunlop Q2(that are better than your pp 2ct,lol)bike wired for gps and phone charger