My 37' foot sailboat can hit 8kts under engine alone at 80% of max RPMs (standard cruising speed), and I only have a 37hp engine. A 45' boat should be able to go faster than that.
I saw a 47' Gulfstar with I believe 130hp that claimed 8 to 9kts with a great layout and ready to go. They have it listed as a motorsailer but I believe it is a Sailmaster which is more of a sail boat then a motorboat. It looked like a good compromize. It is advertized on Yachtworld. Don't know how to post a pic.