Back before my blower days, we swapped over to an alky dominator on my 462 for fun.
2-core Griffon radiator with a Moroso electric water pump drive and a cheesy plastic 5 bladed fan on it.
We drove the GMC all over town, never turning the water pump on, and the motor never got above 160 in stop/go traffic.
I'd think that you could easily get away with it, especially if you were to just fill the block with water and use maybe a 1/2 gallon expansion tank for when it gets hot. Just throw a radiator cap on top of the water neck and hook it to the expansion tank.