I would suggest something better than paper.
Most quality Xerox machines can copy onto clear Mylar sheets. You can get them at most Office supply stores. These clear sheets are more durable than paper. I would look for the heaviest thickness you can find. These are used as clear protective covers on business reports and presentation materials. They are also used for overhead slide presentations. Again thicker is best.
You simply make a Xerox of your actual gasket onto a sheet of white paper. Your gasket will appear dark and the openings will remain white. Then copy the white duplicate of your gasket onto the clear Mylar. What you end up with is a clear plastic sheet with the outline of the gasket in black. You can then carfully trim the port openings with a razor blade or preferably an Exacto knife. You now have a template that can be attached to your heads and alligned carefully to match your manifold bolt holes. Then tape this template firmly into position over the ports. Using Dykem or even a black/ blue permanent majic marker, you can then carefully transfer the outline of the template cut outs to the head surface.
If you do your work carfully, you will end up with an exact representation of your ports that can be used as a reasonably durable template for the heads..and then later on the intake or exaust manifolds to match port the corresponding part.
Just be sure that when you make your original xerox copy of your gasket, that it is as flat as possible and that the edges are well defined on the first white paper copy. Also double check the mylar openings with a dial calipher to insure they match the gasket openings.
Also, for any gasket longer than 11", you can find copy machines that accept legal paper up to 17" long. By fitting a narrow, long gasket diagonally in the image window, you can get about 19" of total length. For REALLY large gaskets, a blueprint shop can reproduce nearly any length, but the limitation will be the availability of long sheets of Mylar. In a pinch you can overlap and tape two sheets of finished mylar together using heavy clear packing tape, after carefully aligning the two completed images.
Some may ask why the extra step of transfering the image onto white paper instead of copying directly to the mylar? First, the image from the gasket directly to the Mylar will often be too light and difficult to see well. Adding the second step results in a dark image that provides a much darker edge to follow on the Mylar. Also, if you make a mistake, you waste only paper. The Mylar sheets are more expensive.
This method works very well as long as you take you time and are careful at each step.
BTW, if your head has dowel pins for locating the gasket, these hole locations can be transferred to the Mylar template for increased accuracy. I use a shim stock punch for making these alignment holes, but a simple paper punch could also work.
There are many variations and uses for this method to transfer irregular shapes and images onto a work surface.
If you need to make a gasket...xerox the image of the surface being sealed onto white paper. Using double sided tape, attach this image to 1/32 gasket material and then trace the outline with an Exacto. When done, remove the tape and paper and...You have just made a new gasket.
On a PC Series Canon plain paper copier you can even take 1/32 or 1/64 gasket sheets, cut them to no larger than 8 1/2 x 11 and feed them into the side loading paper port. It transfers the image directly onto the gasket material as long as the material is light colored....pretty slick.
We don gat to show yu no stinkin BODGES...!!!