The "gaskets" we used on the truck pull MOPAR hemi engines were very soft, so the fire ring wire could imbed into the surface easily. I think some type of "annealed" soft copper would be suitable, as it needs to compress and deform slightly as the head is torqued to seal well and accommodate minor blemishes or less than perfectly flat head and block surfaces. A brush-on sealer like Permatex Super 300 would need to be used to seal coolant- - - -water is MUCH more difficult to seal than compression. Some of the puller engines only had coolant in the aluminum heads- - - -the block cooling passages were filled with hard epoxy material to brace the flanged sleeves we ran. One 547 cubic inch "426" engine I built had the original cylinder walls bored completely through in places- - - - there were stripes of epoxy showing before we installed the sleeves!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!