[Oldsguy]

I drove a '74 or maybe '73 Omega with a 455 in it once. Lots of torquey response with that big mill in a little car. The car needed new front end bushings and tie rod ends so it was almost scary. I didn't notice what kind of headers were on the engine, but I think that the 455 was an option at least one of the years of production although I might be wrong about that. Either way, that doesn't verify that headers would be marketed for that combination anyway. I don't think I have ever seen anyone list headers to fit a 455 in the Omega but that doesn't mean there are not some that fit. There is a guy over at R.O.P. that has an Omega with a built big block in it, in fact I think there is something in his moniker about that, like "73Omega" or "455Omega" or something similar, you might go over there and ask him. Good luck.