Where can i find good quality gaskets for my xr4i MFI? I need the gasket on the plenum and one for the inlet manifold between the heads.

I fitted one from burton power but im not pleased with the quality. It has a steel core which is hard to bend and fit correctly under the inlet manifold.

I remember the Original Ford gasket was some kind of plastic/rubber gasket.
Are these still for sale? or other good non steel core gaskets for sale?