I will be happy if someone can suggests I am wrong, but I haven't found any that "fit".
I bought a set from TA, but the drivers side won't allow for the steering column, and the passenger side might fit in your case because you motor won't be fitting in like a GS400, it will be back up higher. Otherwise the passenger side won't fit without a frame notch.
I bought a set from Poston, but I don't think you can get them anymore. They would fit your car, but the passenger side still needed a frame notch for a GS400.
If you want headers, get them while you are fitting the engine, so you can assess your options.
I did take the Poston driver side apart and fitted the flange closer to the bends and with a couple of dents did manage to get them to squeek past the steering, so it is possible to do it with the original steering.
Good luck,
Bob