Time to Rethink
Is this something you really want to do? If it is an unexpected opportunity, where does it fit in relation to the state of your current project? Is your project nearly done or can your deputy handle it? Or, as its present project manager, would you be leaving your team in the lurch? Such a situation will not look good on your resumé.
A long time ago I faced the same problem. I was responsible for the four-year construction of a very large and difficult project in the London (UK) docks, then in its third year. By coincidence, I was offered the opportunity to take responsibility for construction of the bank portion of the Toronto Dominion Centre then under development.
The offer included all expenses paid for moving from London, UK, to Toronto Canada. It was a wonderful opportunity indeed! After much careful thinking, my response was that I would very much like to accept, but I feel a responsibility to my present project for at least the next six months. The response that I got was a great relief basically: "That's fine just let us know when you are available."
Such offers are rare and seem to come in cycles about every five years, depending on the state of the market for the type of work you are interested in. Meantime how do you unearth such opportunities? First, make sure that you really want to go through with this, and that you have exhausted opportunities with your present employer. If you have a potential employer in mind, do your homework and make sure that your vision is realistic. There's nothing worse that finding yourself in an unexpected employment situation, project or otherwise.
First, learn the "lingo" of the intended environment or project. You will need to be able to talk the talk if you are fortunate enough to be interviewed. This will help to impress an interviewer. Search out the best person to contact for potential new employment. Again, find out as much as you can through your own contacts or through other sources such as attending a relevant conference where you may "bump into the right person" to contact. Do a little soul searching for what of your experience might be relevant to the new situation, so you are ready to discuss the challenges of a new project with the new company.
Second, draw up a list of questions you would like answered, partly to confirm your previous findings and partly to obtain additional information to fill the gaps in your own investigations. Don't ask what the pay is, leave this until later after you are satisfied that this a position that you would really like.
At the interview, don't just sit there and wait to be asked questions. First, thank your interviewer for the opportunity to discuss the possibility of employment with their firm. Then preempt the interview by asking a question about the proposed work, and even get into a discussion about it. This will generally please the interviewer, as they do not have to start the discussion.
If they happen to get in first and ask you to talk about your background, you are quite at liberty to ask a lead question first so that your response to theirs is all-relevant. Chances are that the subsequent discussion will then never get back to a discussion on your background. Discussing the challenges of the new project manager position that you are seeking will be much more illuminating and valuable to you.
Finally, if they make you an offer, ask for time, maybe a few days, to consider their offer.
Here's wishing you good luck with your project management career mapping.