I work as a full time developer in the US. My previous employer from 3 years ago has sold a large startup project in Russia for next month, however their three and only senior developers have recently resigned.

I still have somewhat intricate knowledge of the software to be installed since I was the original author, so my former employer, in somewhat of a panic, has asked if I can take two weeks vacation from my current job to fly to Russia and lead the startup.

Logistically, I can do this and my current employer agreed without issue. Said former employer is very small and hasn't hired contractors before, and I haven't contracted either. The company simply asked my what my salary requirements are. I had, and still have, a great professional relationship with the owners.

I feel like I'm doing this as a favor in a way. Payment is guaranteed, but I have no idea what I should bill for overseas work. If it matters, I was paid around 110k at the former employer.

Just looking for some advice. There are many contracting salary threads here, but I feel that the overseas work throws a twist in things.

Thank you!