I am in the process of changing the cheapies to dougs as we speak. I have a 904 trans with a 360. The exhaust does have to be modified or at least mine does. From the looks of mine I have to have new pipes made from the header to the mufflers.
when I install headers I put a thin film of copper rtv around all exhaust ports. It makes it harder to change gaskets out at a later date but it helps seal up any minor leaks.
sorry to thread jack but when you changed over the headers, did you have to do anything to the rest of your exhaust or did they bolt right up to your old exhaust.
The studs say they are for a 3/8 thread, the heads on the 360 are 5/16. Are you sure these work with the la heads? Just curious because I was looking for a set of studs.
when you change the gaskets out, you could try putting a small amount of copper rtv around the header gaskets. I have used this trick in the past to help seal up headers.
I have been looking too and the answer is no. Though the exhaust kits from a 73-74 should work they just will not have the cats. I think when I get mine redone I am going to tell them I have a 73.