With all due respect, Bill, if you're thinking of trying to go head-on against WGRR, make sure you know what you're competing against.
It sounds like what you're envisioning is closer to WDJO than WGRR these days. Not that there's anything wrong with aWDJO-type format; WDJO has a decent (albeit older-skewing) following, despite a weak signal. But likemost Oldies stations that have gone "Greatest Hits," WGRR is playing quite a bit of 80's now (mostlypop-rock stuff like Springsteen, REO, Prince, etc). The 60's that still remain are mostly from a select group of artists--nearly all Beatles & later.
If you're thinking of dayparting the Oldies into certain hours on ClassX, personally I think the current WGRR approach of mostly 70's, with some post-Beatles 60's & some 80's rock, would be a better fit with the rest of the CX format, and obviously it does well for commercial stations. However, a more "true Oldies" approach might be better for a non-comm, as older listeners might be more willing to directly support it financially.