I had to make a spacer for my new header so I created the CAD file and had an 1/8" plate cut, which arrived today and fit with no issues. Although it went on just fine you can notice the top outside holes needed to be moved out ~0.015". As a result I modified the drawing and posted below. The ports on the flange are not sized to the gasket, but are reduced the entire circumference to better match the head. I will also note my drawing is based on the OEM exhaust manifold gasket. You can modify the port size on the drawing to your desired dimensions since they are centered correctly.





Here is the .DXF file link if you need the drawing....
EVO Exhaust Manifold Flange

 

This is a pic of the spacer flange on my Curt Brown ported head. Same width as the port, but slightly larger top to bottom.




I placed the stock gasket over the spacer from the picture above.

 

where you buy that spacer?
I have a colt 96 with a 4g63awd and i have a facing forward manifold and i think i need to use a spacer like that to separate the manifold from the engine a little more.