i guess my main concern is why i can't get more out of the engine in the rpm range. If i switch to a 3 blade, will that increase the RPMs up almost 1000?

You need to give the right information to get the right answer. What is the pitch of your prop? Make sure your tach is correct. If you don't know how can these guys give you the right answers. 3" of pitch could be a swing of almost 600RPM. One of my best friends has had 2 of these boats. The first had a 330 that did 58gps with a 21 Mirage+ and the other had a ZZ502 with a 22" Bravo1 that did 72. He now has a 557 and runs around 80 with ~630HP. It takes a lot of power to get these boats moving.

thats cause of the x ,prop shafts are to deep a 2'' shortie will help on speed and handling will be better. also find out what size prop you have and if you have the mag which was 330hp in late 87, then came the 365hp mag in 88 and stock 330hp 454. that makes a different on which hp you have.