Good idea to read the outboard threads in the Technical forum. Here on SF Bay, we found the 2-cycle 9.9 to be large and heavy, so most were never left in the well. The current 4-cycle engines require significant modifications of the well and lazarette. For one such modification, check out Ebb's Photo Gallery thread:

http://www.pearsonariel.org/discussi...D&daysprune=-1

Somewhere in the early posts you'll find the modification to his Ariel for a Yamaha 9.9 4-cycle. Since then, he's removed the engine and gone in a different direction.