Hey blade,
just a note I don't believe the second option (900/sbk 6sp into the 750/620) in my post will work. Referring to BB moto one notebook...
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Brad Black &raquo;</TD></TR><TR><TD CLASS="quote">The 6 speed gearbox from the larger engines won’t fit the small 2v engines, due to the shafts being slightly further apart. The new 6 speed gearbox from the 800SS/M engines will fit, and is much the same as the 6 speed gearbox from the 400 engine I am told. Ducati Performance is also offering</TD></TR></TABLE>

Ducati Capacities Dangerous page you have there Brad, makes me want to buy some engine parts from different models to play with.

But when I split the 620 cases, probably this winter or later, I still try a 748 tranny to see what the issues are. Of course if you are splitting the cases and have a 748 tranny around, let us know.