Big Sid found and brokered the deal on my 51 Black Shadow. Big Sids Vincati is a great book but "Vincents with Big Sid" is my favorite although it may be hard to find. It covers US history of the Vincent really well. Lots of stuff on drag racing. Unfortunately Bid Sid passed recently and will be missed.
The third "New Vincent" bike pictured uses a stock style engine but lost a lot of power to meet emissions. That is why they decided to go with a "new" engine in the "new" Vincent. Plus they wanted to carry on the Vincent speed heritage and be competetive with the best. They almost put the Honda RC51 engine in it. It was very, very close. IMO some things are better left alone.