This sounds like paid overtime to me.  Federal Fair Labor Standards Act
does not prohibit such payments but it is certainly not the norma.  (Most
institutions like to interpret "does not prohibit" to mean "don't pay"!)
However, whatever policy your Provost decides upon, it must be enforced
and paid fairly across the institution whether or not it is for
research.  Salaries paid for research must be in accordance with the
policy for the entire institution even though a portion of their salary
has nothing to do with research.  I hope this is not over-simplification
for you -- I apologize if it is:  I wasn't sure from your message if you
realized this.  Therefore, assuming ALL other things equal, if Prof. A
gets a salary of $110K/yr which includes $X for overload, then Prof. B
(who is partially supported by a research project) must have a salary
base of $110K/yr if he/she has the same overload.  I think you would have
a hard time justifying paying this bonus to Prof. A but not to Prof. B.

Also, I think the issue of the definition of "academic overload" might
become touchy.  How will you handle the following situation:

Prof. A has no formal research projects (but clearly must publish or
perish) but teaches X classes; Prof. B has formal research projects (that
clearly define his/her percent of effort) but teaches X-1 classes.

Good luck!  I'd be interested in other responses you get.  You're welcome
to include mine in a summary if you decide to publish that to the group.

* * * * * * * * * * * * * * * * * * * * * * * * * *
* Evelyn J. Ford, Research Administrative Manager *
* Neurosciences Research Center                   *
* Allegheny-Singer Research Institute             *
* Pittsburgh, Pennsylvania 15212  U.S.A.          *
* xxxxxx@singer.asri.edu                            *
* 412.359.4475 voice                              *
* 412.359.4499 fax                                *
* * * * * * * * * * * * * * * * * * * * * * * * * *