Scott, more information to address your question. Personally the 200hp D3 and Yanmar 180 are going to be close performers. It is a semi-displacement hull so it takes a great deal of HP to push a boat faster in the water. The Ranger never really planes.
I started this thread last spring with the hopes of getting a lot of responses so I could put an average performance spread sheet together for each model. The responses were good but not many so......
viewtopic.php?f=2&t=17591&hilit=performance&start=15#p116058
There are a few R27 that have good data for you to look at.
Things that can reduce performance:
Prop out of balance or damaged
bottom fouled
Boat loaded with gear
passengers on board
trim tabs not adjusted properly
........
You should realize a 8.6' beam boat that is stern heavy will have a significant performance change with added weight. I had a C26 with a 220 hp D3. After equipping the boat for cruising and loading it with supplies, fuel and water the best performanceI could get was 18kts 2 passengers on board. Add 2 more passengers 16.5 its. I did have to reduce the cup in the prop in order to maintain Volvos recommended WOT of 4000rpm. When I sold the boat I sea trialed the boat. All gear was removed except for the normal equipment needed 1/2 tank of fuel, half tank of water, 4 passengers and the prop was recouped to the original number .105. The same boat that I was cruising in with 2 passengers was now running at 20.5kts with 4 passengers in it and with 2 passengers I was able to see 21.5kts. The D3 are great small displacement engines, real "torquee" for 2.4L but that is what they are 2.4L.
My advise is check the bottom, check the prop, check WOT you must maintain 4000rpm at WOT if you want any type of longevity from this engine. If it is not turning 4000 rpm or more find out why. depending on the load you should be close to the boats posted in the thread above. Those number are real!