I. Introduction
II. Financial Disclosure
III. Conflict of Interest
IV. *Representation*
V. Misuse of Position
VI. Other Laws/Regulations
VII. After You Leave
VIII. Where to Get Help
You said: A. You tell them that you can't take the job.
That's right!
As you correctly decided, the problem is that you are going to be representing back to the Government on the very same particular matter involving specific parties that you are working on. That's a violation of law (18 U.S.C. 205 to be precise).
Superb! Now let's investigate the area of "misuse of position".