Welcome to the forum.
The Bronco's don't seem to me to have much of a following. It seems to me that your first decision, that is to bring the 250 back to life, is the smartest decision you could have made so right out of the box you are doing well.
I have some spare parts but they are street bike rather than scrambler parts, but I will continue to monitor your posts and needs. You'll find other people as well on this forum that will step up to help you if they can.
As far as mechanical help goes, I have always found the people on this forum to be there for me as I am sure they will be there for you.
Not trying to implement a 100-point restoration will save you a large bundle of money.
Keep in mind that Ducati in the 1950s and 1960s used the same local (Italian) suppliers as the other Italian marquees (Parilla, Gilera, Benelli, MV, etc.) were using; suppliers such as CEV, Aprilia, Veglia, etc. and so if you don't restrict your eBay parts searches to "Ducati
this" and "Ducati
that" you can find parts that fit, that are authentic to the era, that look to be the right part visually and will fool everyone except only the sharpest experts and stretch your budget in the process. Unlike now there was no 'branding of these bits to match the marquee of the motorcycle they were being attached to.
Be patient and be thorough and you will be rewarded with a gem of a motorcycle when you are done.
Jim
http://www.ducati.com/history/60s/scrambler/index.do