What quantitive metrics would reviewers in order to be presented as candidates for peer review?
If I had to find peer reviewer for a field I have no knowledge of, but a lot of data, I would first come up with a citation graph and look at all papers near to the paper that should be refereed. 

If I had a list of reputable journals, I would filter that paper list by this list. The resulting paper list can be scanned for authors. Now you can compare key words of the important papers of the authors to the key words of the paper. This allows you to come up with a list of persons that may be "experts".