need more top end speed out of my ranger

i have a ranger 491vs comanche with a 200 optimax with a 6 inch manual jackplate with a 24 pitch, 4 blade prob, which is not in very good shape. I just purchased the boat and the compression test on engine all checked out great, but when I took it out. I had 45 gallons in it and 2 people. My top speed was at 55 mph @ 5500 rpms. I was disappointed with the top speed. the boat is 21 ft 8 inch, and it got on plane very quickly. My question is, what should I do to get more top end speed? Raise the motor up on the jackplate, get a new prop, or have the prop I have worked on?

Get a bigger motor. That's a lot of boat for a 200. Max rating of a 491 is 250 hp.
A 23-24" Tempest Plus might get you in the high 50's. Start at 3 1/4" pad to c/l of propshaft.