Obviously, you'd need to ask Bear or gregoryp for the AvHistory stuff; Bear is generally a little easier to get hold of. I'm sure they'll be happy to grant permission.
The original model builder obviously should be asked, assuming he didn't grant overall permission in the original issue. Some, such as Mike Wholaver, do - but even then, it's polite to ask.
And whoever did the original FM/DM, if you're using it or basing your work on it. As you say it's the stuff from the stock FW190, then you can drop this bit.
If you can't get hold of the original model builder, then the usual thing is to include his "Read-Me" in the package, and in your "Read-Me" you give full credit to him and state that you were unable to obtain his permission directly, but would be very grateful, etc, etc.
Speaking from experience, most modellers are very happy to see their work being given a bit of extra life, and will agree readily to any positive suggestions. Some even agree to go back to their work and tidy up loose ends which they hadn't noticed at the time.
Moral of the story - make a genuine attempt to talk to the people first, but if you fail to get hold of the model maker, release it anyway and hope for the best!
