you can order them on amazon, your local automotive store, etc.
always use STANT (that is what Mercuiser used for years and that is what CHAMP heat exchangers used)
you cant get both with a prop
to get a better hole shot, you need to go down in pitch
to get a higher cruising speed, you need to go up in motor hp, change gears and go higher in pitch
you wont know until you now put it together and find out how far you have to drop in pitch
about 200 RPM for every 1" of pitch.
what prop do you have now?
With the wrong gearing, you have to drop down in pitch on the prop. If your current prop is a 21 pitch, you can drop to a 15 or 17. However there are not props below 15.
I would get the right gear ratio
Use summit racing website to get part number. Then Google around. Summit will match prices. When I get home, I can look up part number. (I think there is a pic of the box in my build thread). Currently at doc office