Sounds like the MH uses the LONG version of 454 WP. Hi volume may not be needed???It is my guess either of the long (7.28 vs 5.17) WP's would work.Talks about CW/CCW rotation in marine app.
with twins they may run one backwards.
I am beginning to think the only real difference we need to be concerned about in a 454 MH is that we use the long (7.280") water pump. Heavy duty bears would be a plus but doubt if high volume is needed. Expect that is more for a 454 making 600 HP and not 200. :)
Again this is my 'guess' since it was 2007 since I really thought about this issue and never grasped it at that point. :)
If the 2.1" shorter one is used one it is not going to pull the air through the radiator as well because it would be just beating the air more by sucking it in from the engine side and not the radiator side?