Some all-time highs (probably outdated now) from players like KME, NES, and (route legend) MCC have been compiled at Mike Mahaffey's page: http://www.pinballreviews.com/hs.htm

There have been various pinball high score pages in the past, but for the reasons mentioned above none of them should be considered authoritative. It really just doesn't make sense to compare scores between various machines (or even the same machine over too long of a period of time). The site I linked above, however, should give you a good idea of what has been (and can be) done on many WPC-era games.