welcome. hopefully at least something out of my last post will turn out to be useful for you.

the "magic number" again goes by a lot of trial and error. if you want to get very "technical" about it, if you locate a good recording of close proximity (i.e. date) to the one you're working on, i believe you can use Cool Edit's "find beat" function. (it's likely called something else, but i can't think of it off the top of my head right now.) then, compare the appropriate beats in the "normal playing recording" with the beats CE locates for the same portion in the fast/slow playing recording.

my less scientific method for this is just listening repeatedly to a correct-playing part of the same song from a nearby dated recording over and over. after multiple listenings to the same intro/part of a correct-playing show, the beat sort of melds its way into your head. then, you can more quickly find the 'magic number' for the incorrectly-playing recording.

also, if you have a decent set of ears (which i'm sure you do ), then you should be able to narrow down the possibilites quickly by listening to the singer's voice and the guitars... the pitch really is a big help in finding that "right sound."