I tried a set of 79-93 shortie headers on my 68 they were into the steering box.I bought a set of hedman shortie headers for the 65-73 ,I had to reconfigure the dipstick tube on the aod and the header ends need to trimmed at the end sparkplugs to be able to get a plug socket on.may work on the 71-73 is'nt the engine compartment bigger on those years?
I've got the Hedman shorties installed on mine. As the previous post states, I had to take a Dremel to the ends of the flanges to allow the sparkplug socket to fit. I don't have the AOD so don't of any issues with it. They do fit very well, almost better than manifolds. So easy to install, after the "factory" paint burned off, I removed them, sanded them down and repainted with high temp paint, all from the top. I only had to get under the car to bolt up the collectors. They still look good after about three months. Summit has them for about $105.00, the cheapest I found when I was looking.