I'll go with the others on this and just say this isn't a good idea
for reasons already stated. oh what the hell, it bears repeating.
Changing weight distribution, bad idea. Diesel to gasoline, bad idea.
Straight drive to stern drives, bad idea.
If you just want below decks storage , maybe you can create storage
space where you were thinking of installing the stern drives.
Rick

On Sat, 18 Oct 08, Ted wrote:
Is anyone familiar with the challenges or benefits of replacing a
typical diesel marine engine with a stern drive engine?

I have an older, 40 foot wood boat with a single prop Detroit Diesel
6-71 that is located approximately midship. To create more room below
decks and add the security of having two engines, I am considering
removing the old engine and installing two stern drive engines near
the bow, just below the cockpit.