It just occurred to me that I didn't answer the last part of Walt's question.
What to do with Blood and Vigilance is especially sticky as conversions go. The classes wouldn't be needed. Modern20 uses 6 classes and will never* have more than 6.
Between the 6 core classes, being built on a feat per level, occupations (that you can change), advanced occupations, hobbies and such, you won't need more classes.
The B&V disadvantage system is part of the core.
So what that would leave would be the powers, which wouldn't change much, and the campaign advice.
I'd end up tweaking and adding some things I'm sure, and there would be new occupations, but it doesn't seem to merit a book all its own.
Maybe in the GM guide I'll do multiple settings, like True 20 did.
*Never say never I know, we'll define "never" as 99% chance.