Two 225 Mercs?
The 150's will make the boat fly, and in my opinion all of the motor you'll ever need. I have seen someone with a set of 200 yami's and it was insanly fast. I have the same boat (74 Tsunami) as you with twin 150 yami's and its a 50mph boat. Fast enough. I'd fear the larger 225's would add too much weight to the transom even if you raised the deck. I'm not an expert on seacrafts, thats just my opinion.
I can tell you this, your boat will easily plane and cruise with a single 225. Mine will plane easily on a single 150 and top out on a single motor at 24kts with 150 gal. of fuel.
I fear you will get poor handle performane in seas due to the transom weight. But... It will be fast
