Exhaust gasket material

I recently picked up a 1971 Chrysler 20 hp for cheap. The guy I bought it from said there was water in the cylinders and the intake gasket was the culprit. As far as I can tell the only possibilities are the exhaust cover gasket, the head gasket, or a cracked block. Some of the powerhead was disassembled when I purchased it so I'm going to start by making new gaskets for the exhaust covers, intake manifold and reed plate, transfer port cover, carb (to intake manifold), and possibly the cylinder drain cover. My bet, as of now, is that the leak was coming from the exhaust manifold. I haven't found anywhere to order gaskets for this motor (202HB) so I will be making the gaskets from gasket material. My question is: what material should I use for the exhaust gaskets? I know on a car they're generally metal gaskets but, since there is fuel, oil, and water to be concerned about on an outboard, I'm not sure of the proper material. It'd be great if someone could point me in the right direction. Thanks.

P.S. I plan to replace these gaskets and compression test/leakdown test. Then, if everything checks out ok, run it and see if I'm having problems with water in the cylinders. If so I'll replace the head gasket, which I think I can order. If the problem persists it'll be time to shop for a new power head/block or part out.

Just for testing purposes, I use aluminum roof flashing or the same gauge in brass.
Good luck.

Thanks for your response. Would I be able to use something like this:

https://www.google.com/products/catalog?q=gasket+material&hl=en&prmd=ivns&bav=on.2,or.r_gc.r_pw.&biw=1280&bih=874&um=1&ie=UTF-8&tbm=shop&cid=4637040993943370224&sa=X&ei=PdNOTqmQDIqKsgKqnbnCBg&ved=0CHkQ8wIwAQ

That looks like good stuff. How are you going to cut it?

I'm not real sure. I have a flex shaft tool for my dremel that might work well with a little cutting disk. Otherwise maybe put it between to pieces of 1/8" plywood, copy the template on that and cut it with a jigsaw.