I have a set of (NEW) Hedman 65003 headers for sale. 1 3/4 x 3". I'm going with 1 5/8ths. These come with everything you need...even flanges.
They fit 67-69 Camaros and 68-74 Novas with 283-400 engines. $200+ tax at Jegs. Selling for $180 shipped to your door.