The guy that bought my black widow (same engine and drive package as yours) got more dang manuals from me than you can shake a stick at.
The owners manual is generic and a waste of time unless you are new to boating. If you are new to boating, a Donzi is probably not a boat for rookies. However, the 24 black widow is super easy to drive and does not require a learning curve like the classic models.
There really is not a good manual that covers the boat. The manuals you want are the genuine OMC king cobra stuff ala engine and outdrive. The rest of the boat, just ask questions here and you will get good correct answers along with some sarcasim and humor.
I got my OMC manuals on ebay. The aftermarket generic stuff like seloc, chiltons, etc. are good. The OMC factory stuff is even better.
PAY ATTENTION - EBAY ITEM 140235273994 is for sale NOW. This is the manual I had and is excellent.
Tuco: When you have to shoot, shoot, don't talk.