You'll have to find copper wire the right dimension for your o-ring. Go to Lowes and check the house Romex.
Beat the wire into the groove, then get out a fine file and go at it until it's flat.
You can then go back to using regular head gaskets.
I've run copper on the street for years. Never had any leaks... Just make sure the heads/deck isn't warped and that you silicone around the water jackets well. The copper makes a great heat sink between block/heads.