2 stroke or 4 stroke engine?
3 blade if speed is your objective, 4 blade if max thrust is the better plan.
19p obviously way to big.
Our Honda 90 on our lightly loaded 24' toon likes a 15p 3 blade (5500/26mph), or for neck jerking hole shot (pulling), a 13p works good (6100/24mph).
A similar 75 on a lightly loaded 'toon should work good with one of those props, or maybe with an inch less pitch. Noteworthy maybe, is that the 4 strokes sound kinda busy when run at max rpm (6000). Sound MUCH better and are sometimes faster when set up at 5500.