Options to repower a 33' Larson

[zealer]

Hi all,
Contemplating my biggest project yet. Found (what could be) a really good deal on a 330 Larson. However, it has no engines or drives. Was originally set with a pair of Mercruiser 7.4 MPIs and Bravo 3 drives. Just the transom assemblies, exhaust y-pipes and steering assemblies are left in the engine bay. I am considering a dual 4.3/5.0/5.7 Alpha One swap instead of dual 7.4 MPI/Bravo 3 for cost effectiveness.
I am no stranger to in-depth mechanical work. I understand Bravo 3 drives have a couple extra holes through the transom that would need patching. Not sure about engine mount difference between big block and small block (but I will soon verify).
The area I lack knowledge in is the Mercruiser MPI motors. I've only ever worked with and swapped carb'd motors, and had all the existing provisions in the boat to do so. In this case, I'm not sure about the wiring and cables. And I'm not sure what exactly is missing.
Thoughts, info, suggestions?

 

[matt167]

Find the reason the boat was turned into a parts boat and that will determine your good deal or not.

If you have the transom assemblies than you wouldn’t want to go to an Alpha. Just need 2 identical 5.7 engines and matching outdrives. You should be able to convert to carb pretty easily.

 

[Scott Danforth]

I wouldn't go down in power or drop down from the Bravo to an Alpha

Two 502 BBCs, or two 6.2s, or two 6.0s or two diesels. Big hulls need torque. 4.3 or 5.0 won't cut it. A pair of supercharged 5.7s maybe.

If you're wanting to go carbed, I would most likely build two 6.2 aluminum LS based motors with full system heat exchangers and run carbs in a victor jr intake

The wiring in the boat will support anything, and a simple harness swap to the helm may be needed if you want to upgrade to NMEA 2k (easier with EFI)

I agree to find out why it was stripped. Could have been a marina queen that got left in salt water and the manifolds failed taking out the motors and was scheduled for a repower or it could be a rotten mess needing full restoration that was stripped of the good parts and they found out disposal is expensive and want to sell you a headache

Being the original engines were 7.4 EFI, that puts the boat at least 26 years old.

 

[KD4UPL]

I'd never consider less than a 350 Mag and a B3 x2. Anything less will be horribly underpowered.