I have tried a 140mm mag, on a 927cc motor, based on the 66e, and it cannot handle the power. It does OK on the mid and top end, but the bottom end cavitates really bad. The 144mm mag works good for that application, so does the 148mm. But, on the REV12, you have to start with a 148mm mag. A 144mm will not handle the power, I have tried it. So in conclusion I would say the 140mm is good for a max of 150hp, the 144mm is good to about 180, and anything more than that use the 148mm. Just my experience.
Jeff