I would hope that I should be able to get about 6000fpm out of a 757/767. Of course there was an aircraft many, many years ago that could do around 26,000fpm but I shall not mention its name here as it is forbidden with in the company!
I have heard as well that if you sideslip a 75 it simply falls out of the sky...whether you can get it out of the sink of course is another matter...
Kind regards,
yours aye,