Upgrade 180 hp 43LX to 315 hp 57L

"Looking for opinions here or

"Looking for opinions here or advice from someone who may have done this mod.
I have a 1996 Blue Water Mirage 20' 4" with the 4.3LX Alpha One package. Runs just great; no problems ever. Only has 280 hours total time.
I see that you can buy a brand new 315 hp carbureted 5.7L engine package complete from Michigan Motorz for $5999.00 plus shipping, that will work with the Alpha One drive. Merc says the Alpha drive will handle up to 300 hp.
The engine compartment will handle the engine length OK, and all else looks doable. So it looks like I could add about 135 hp whilst only adding about 100 lbs of weight.
So has anyone out there done something like this?
What am I missing?"

Done it several times. You wi

Done it several times. You will need to regear the drive to 1:5 from 1:84. Also recommend a drive shower to cool things off.

Thanks boatrep1 for the inform

Thanks boatrep1 for the information.
Can you tell me more about the drive shower. What is it and how does it work?
Thanks.

"Rod, I think the added HP wi

"Rod, I think the added HP will be ok. My neighbor has twin 454 CID/Alpha 1 Mercruisers. I recommend you be a bit careful with the throttle, however . You will also need new exhaust manifolds, or do they come with the package? You may be able to get a new prop to compensate for the gear ratio change boatrep1 mentioned."