Follow the back right edge of the block about three inches forward from
where the block begins to curve to a brass fitting. Using a deep well
13mmm socket carefully loosen the fitting and coolant will dutifully
drain onto your foot. If you attach a piece of hose after the fitting
has been loosened but not yet flowing you can direct the other end of
the hose into a drain pan and then control both the flow and direction
of the coolant. Loosen the overflow bottle cap to allow the system to
drain. The radiator will still be full to the level of the petcock,
since ot os there primarily to drain all the coolant from the block so
that when or if you were to remove the cylinder head you wouldn't
contaminate the crankcase with coolant.

Bob