You would want to pul the headers and have them machined flat if you are going to try not using a gasket. You could cut the scallops out of the oem gasket and use it in sections. If you are using studs it would be easier, if not spray some of the copper gasket spray on them and it should help hold them in place during the installation.

You can also buy high temp composite gasket material and cut out new gaskets. I am not sure how long it will last, the gasket I made for the turbo on my Supra appears to be working, but the Supra is still in its restoration, so there hasn't been much time put on the gasket.