3 places: Hemmings, Ebay and Autotrader.
Photos are digital gold.
Ebay will get you exposure...good and bad (people emailing that radio knobs are not OEM)
Hemmings is $15, and gets the broadest classic buyer audience; I have yet to not have a sale via Hemmings.
Autotrader is more local, and results in actual buyers, not tire kickers
Craigs is tirekickers/nonsense, ex-for salvage.
Dont be cheap on photo options; saving $15 that will bring $1000 more makes no sense.
Take about 25 photos (all 4 sides, 360 degrees of interior; pull up mats on floors, trunk, and 4 wheel wells), open hood; layout all receipts on a large table and photo that too.
Take a short video of car starting / idlinging, walk around, show inside and guages (oil pressure/temp, odometer); ebay allows videos or you can send to people via email link.
If you dont have a good digital camera, buy one for $150, take pics/video and return it in 7 days.