volks ,
When I replaced the rear core in my 85 ,I bypassed the bleedind part
altogether .
How you may ask !
Well the FLAPS down the road sells plyer type hose clamps (they pinch off the
rubber tubes during cooling system work ).
So they isolate the rear core during the replacement procedure.
I lost about a thimblefull of coolant during the replacement .  To get 'round
the bleeding part when I put the new core in ,hook up the hoses to the core
and fill it with the whole assembly raised as high as it will go. then remove
the clamps .after that top it off,seal it up and bolt it back in place . I
found this to be sufficiant to fill the system as you can raise the whole
thing higher than the res.tank in the engine bay.
                                         In a pinch (hehe ) two parrallel
type vice grips and some thin pieces of wood (paint stiring sticks perhaps)
will do the trick as the hose clamps

godd luck
mike 85 westy
203k