Drywaller, the 11x7.5 is an excellent starting point. The engine I assume is new so that will let it turn extra RPM's but It will be loud. All the feilds I fly at have noise limits so I am forced to use larger props (I use 12x9's on all my .60, which yeilds a sound level of around 92db), an 11x7.5 will yeild a 99 to 100 db while new but as it breaks in that can climb as High as 104db. If you don't have that restriction great!
My bet is you will like the 11x7.5 just fine but if you want to change props. You need to get a rpm reading while out at the feild. Once you have that you can find your top horizontal speed with the formula:

(RPM X Pitch) / 1056 = MPH.

RPM = Rotations per minute
Pitch = Pitch of the prop. In inches
MPH = Miles Per Hour

If you want to change prop.s you need to be able to compair them without having to buy them. You can do this with the formula:

Dia x Dia x Dia x Dia x RPM x RPM x RPM x Pitch = Hp
140000000000000000

Dia = Prop. Diameter
Hp = Horse Power

Pluging in the RPM's you got for the 11x7.5 you will get a Hp. We can plug that Hp into the next equation:

Cubed root((Hp x 140000000000000000) / (Dia x Dia x Dia x Dia x Pitch)) = RPM

Then using (RPM x Pitch) / 1056 = MPH we can see what that prop will do to our top speed in relationship to the 11x7.5 we alread flew it with.
Good luck.