Hot Rods Coolant capacity for a 392 hemi 1958

I’m trying to flush out all the coolant from my 58 392 hemi and I want to put Evan’s waterless coolant. Did the prep fluid put in about 14 quarts drained it out but only got 12 quarts back. Does anybody know how much coolant the engine alone holds, radiator completely drained block plugs were removed bottom hose remove removed thermostat housing removed blew in air to remove all the coolant that I can. I need to get to 3% water and I feel I still have maybe water in the block.