Come over as “senior” to a Big 4.

I'm a senior person in a consultive technical specialty. I'm being recruited to go to a big 4 firm to start a department. How flexible are big 4 firms on starting high up the food chain in title and salary? I'm making over 300k now and don't want to go backwards – should I be asking to go over as a Parnter or Director? Also, what is a Senior Excecutive? I've seen a wide variety of info from promising to not so promising on this. Thanks!