go for a v8!
I have a big block and love the sound and power! But not a great fishing boat. It loves to pull tubes and party lol. Where are you planning on boating? First thing i am goign to tell you and i was told and didnt believe it. BOAT stands for break out another thousand! And dam do they cost money. I might be looking to sell mine this spring due to just that. Looking for a 223ls Formula with a 454?
Also check out speedwake.com if your into speed boats very good site.