Thank you very much.
I understand exactly what you mean. Changing the spacer sounds like the way for me to go if I chose this boat.
I'm going to look at the boat again this Saturday, and I'll check the mounts for room to move, although I assume the PO would have...well, wait...you can never assume.
Today, and it seem to change daily, I am leaning towards the "Atomic 4" boat using the reasoning that the 5411 may be underpowered for the Catalina 30. I mean, how many have actually blown up? Isnt that the concern?
As far as the cooling on the Universal 5411 goes, I have found out that this model had an "add on" available for a closed freshwater cooling loop which was in ADDITION to the raw water loop. That, of course, adds another pump.
Again, thank you for thoughts, they are a great help.