My friend has a very similar set up to what you are talking about. Here is what I can suggest. Take the amp that comes with the boat out and put in the 900/5 like he did...huge upgrade, factory amp isn't enough IMO. Either trade-in the amp Mastercraft gives you or sell it on Ebay or something.
Tower speakers...use whatever amp is running your Rev 8's currently. For your sub, use your current amp as well. There is PLENTY of room to mount things. My current plan is I'll be pushing a little over 3000W through 4 amps...200W to each of the 10 JL7.7's 200W to the free air, and 1200W to my ported sub.