As above, also are they 8BA type heads? If so, normal 8BA gaskets, I prefer copper as I can usually reuse them if I'm pulling the heads for a peekaboo. Some are scared that the copper will promote corrosive electrolysis twix the dissimilar metals, which is scientifically correct, just the aluminium heads I've seen used with copper or composite gaskets all have the visible corrosion where there is no gasket contact. So in my experience either is good, I hate cleaning that composite gasket stuff off the block and heads, on early engines with studs, the devil's own work. Obviously the sticks to everything composite gasket is a one use deal, so a peekaboo is costly in time and money.
Your choice.
On the corrosion, how do the heads look around the water holes? Especially around the big wobbly holes behind the back two cylinders on each side, they get awful close to the combustion chamber back there.
Plug threads good? Sender and heater tappings good? How deep is the chamber over the top of the valves?
Martin.