So I'm leaving Florida on Tuesday and heading for the cold north. I'm going to winterize the boat down here because I dont wanna take a chance and not get to it in time. I've got the kit with the hose and bucket up home but not here. Can I just drain the block and fill it through the thermostat?
I had another idea, tell me what you think of this. Remove the thermostat, reinstall the houseing to the manifold. Remove the oil cooler hose and begin filling the block through there. If the hose is tall enough it will fill the block/manifolds and all the coolers and run out the exhaust. Is it that simple or no?

It's a 7.4 MPI.

You can drain the block and all hoses on the exhaust and oil coolers and then remove the tstat and fill through there. It would probably be fine just draining all the water out.