My guess is most of it.... Or more than half in the engine.

What vehicle is your 440 in? Never needed to measure it on mine. Suppose you could remove the thermostat, close off the bottom hose, fill then drain and measure the quantity if no one else has a quick and easy answer.

Considering the system, there is space for water (or coolant) in the upper and lower hoses, heater core, heater hoses, top and bottom tanks and tubes in the radiator; All the rest is in the heads, block, water pump, etc.

Here is a link to vintage cooling system capacities:

http://vintage.mitchell1.com/PClubData/chassis/den73/V2D735217.pdf

Total coolant system capacity, (guessing roughly around 18 quarts or 4 1/2 gallons) less items above.

Perhaps a Radiator Shop person can check in. At least you have a reply and BTT.