Z-25 Engine upgrade

[KerrLake]

Hi Guys... I am taking out my engine to do transom work on my 86 z25 and want to do some upgrades or a possible total rebuild depending on the condition when torn down. I have the 454-370 (the best I can tell by the mercruiser manual, it lists a 330 and a 370 and I was told the high rise manifold should mean 370) with about 550 hours and the trs. I want to keep the engine at a very reliable level, but want to get as much hp as I can without spending a ton of money that I won't get back out of the boat. I'll change the exhaust and carb as well. What would be the concensus on keeping a reliable boat that idles! By the way, the best I've seen on GPS is 57 but usually around 55, does that sound right?

[farmer tx]

What RPM are you getting your 55-57 MPH at?

[DAULEY]

since you are redoing the transom plug it and change to a bravo with a higher x demention same motor you should see in the mid 60s tolow 70s with fresh motor

[KerrLake]

I'm turning 4600 WOT. I don't have bottom paint either. How would a Bravo setup give that much difference in speed? By fresh engine do you mean souped up or rebuilt fairly stock? I've read that the bravo swap gets pretty expensive as well. The trans gets ditched with a bravo setup doesn't it?
Brian