My O-235 with a fix pitch prop turning 2350 RPM at TO would accelerate to 145 kts at 2750 RPM, top speed at 3050 RPM  was 180kts at 1,000ft altitude. It weighted 935 pounds empty. The adjustable prop on the O-200 should develop more Hp at the prop TO speeds than my fixed pitch prop on my 115HP O-235. I would check the pitot system, RPM indicator, and lastly the prop efficiency in that order. You can borrow my Prince prop (62/69) if you feel the prop is the problem. Don G, the Lancair test pilot required a static 2250 RPM with the O-235 before he would test fly a new Lancair 235.

Rusty