I can't speak for a pilot house Parker, but my 23 SE runs very well on a 200-hp HPDI motor. One of our local light-tackle guides has been ordering his new 23 SE each year with a 150-hp 4-stroke. He feels that this motor is adequate for the hull. Of course a pilot house has greater weight and air drag, plus the hull probably has more dead rise than a 23-SE.
Hopefully another of the Classic Parker brethren can tell you more about the pilothouse performance.
If you are getting a 4 stroke 200hp i think it will be underpowered. 250hps are not that much more at this stage of the game. Just my opinion Good Luck!
I own a 2004 Parker 23' P House with a 200 Hpdi Yamaha. To date, no problems. Good fuel economy. I cruise at 23 mph, which is comfortable for me. Boat will do 30 to 34 mph pegged. Anthony at WhiteWater advised me to get the 200hp, and I'm glad he did. The 250's from what I understand were loaded with problems. Hope this helps.
Tom