I really like it big and heavy is the best part lol 55 would make me happy, I am not trying for a race boat here just want it to go a little better than its supposed to

Absolutely, a stock 454 mag would be perfect, torque is what's going to get that boat moving. The only way I'd consider a small block is if you did a 383 stroker that's the only way you'll be in the same realm of torque as a BBC

Going to need a Bravo in front of it though.

Don't feel bad.. I can only hit 40mph on my 260hp alpha one but I'm running a 19 pitch ss prop.. My tach is only reading 3800 rpms but I'm pretty sure it's wrong. Haven't had a chance to check it yet.. Was thinking of dropping down to a 17 pitch to try it. Keep me updated on your progress cause I would love to know what to do to hit 50 without spending thousands of buying a new boat lol