If the fuel choice is Alcohol----
Iron block and iron heads--- then no cooling is needed, leave the core plugs out to let it vent
Iron or aluminum block with aluminum heads then water only in the heads to keep center exhaust area from burning out
if the plans are o-rings then the alu head gets the o-ring and the block gets the reciever groove, again to keep the exhaust area from burning out
You can use MLS gaskets for Iron blocks and heads, I havent had good results with the MLS gaskets with aluminum and best to go with copper if the engine is blown