Yeah they put 273s in B bodies also. I saw a 68 Plymouth Satellite once that had a 273 under the hood. but yes you are correct on that price, for that money you want to have one thats ready to go doesn't need much but maintenance.
I would take 64 or 65 B body with a 273 in a heartbeat. They were all 2 barrels but it doesn't take much to throw a 4 barrel on them and dress them up like the HP's are.