From the criteria you've shared, I'd second looking for a good FWB 124 (or a the 22 version, the 127). They're a classic, hit your velocity mark (and then some if you have Maccari work on it). There's a ton of them out there and parts are available.
IIRC, the Crosman 6500 is a rebadged Anschutz 335. Not sure how supportable those are these days. I believe they had leather piston seals, so you might want to take that into account for longevity and supportability sake.
If your budget allows, a TX200 is a huge step up for not a lot more money. After that it's a used R7, R8 or their Weirauch brotheren, the HW30, HW50 or maybe a HW35.
Different option...would be an old Benji or Sheridan Pumper. I'm gaining a renewed appreciation for those after having been around the block with the more zoot stuff.
