All the auto parts store calipers will be about the same as they are all rebuilt stock units. Just try to find the best price and warranty on them(though AutoZone, Advance Auto, and OReillys offer calipers with lifetime warranties and Napa a 1 year warranty) on them and go for it. There really isn't much on the calipers to be rebuilt, basically they just clean them up, but a new bleeder valve in, and put new piston seals in, and maybe even a new piston if need. Just be sure to get the proper replacement caliper as the 9C1s used a "heavy duty" caliper designed for a thicker brake pad than the civvie and Impala SS's got.
You can probably just pick up the rebuild parts yourself and rebuild them, the FSM's and even they Haynes book for our cars tells how to rebuild the calipers, if you want to go that route. - Peter
I recall calipers are a core charge item anyway. If possible just yank yours off first and make all the physical matchups you need to at the store. Same idea if you want to rebuild yours. For oem type replacements I'd say good bi-annual service to the slidepins would be a LOT more important than the brand or where you buy them.
Some AAP have AC Delco ceramic, some don't. Gettem if you can.
The "HD" calipers may not mount to the standard caliper spindle. The Parts manual for our cars lists separate PN's for the spindles for the "HD" brakes and the standard brakes. Unless your car is a 9C1 or 9C6 it most likely has the standard brakes. Look at the SPID list on the trunk lid it lists code JA9 it has the "HD" brakes wheras if it has JB9 it has the standard brakes. One plus side of the standard brakes is that the calipers are about $15 from most stores(excluding core charge) . Honestly the "HD" brakes don't make that much of a difference just an ever so slightly thicker from brake pad(21mm instead of 20mm). - Peter