I have inspected the wheel wells at a pit stops and it does get hot in that area, a vent would certainly help, the original engineers wouldn't have put them there for aesthetics alone.
Without a suitable vehicle to liberate the original parts from, the closest looking I've found so far online are marine inboard side vents, much like the ones seen on the glastron, but these vents fiberglass! There's lots of 'stick ons' which would be ok if I wasn't looking for functionality, or vents for an escalade, ford f series and land rover, but none for a AS classic. Maybe its time to customize.
Just venting | Cartype
I think the one they put on the Cadillac would like good on my 345