marina will pull the boat this week and set it up on blocks

i have a freshwater cooled engine, with a heat exchanger. my plan is
to pull the hose leading from the seacock and put it in a 5 gal bucket
of fresh water to flush the sal****er out.

then fill the bucket with 4 gallons of propylene glycol (the pink
antifreeze) and flush this through the engine, out the exhaust
manifolds and through the mufflers...

is this going to be enough? how fast is the engine going to empty the
bucket at 1000 rpm? any other secrets i should know about?

thanks much all