Paul, as you have probably read in another long thread about this very subject, you are not alone. Several of us are trying to come with a viable solution that we can all use to deal with these pumps.
Stay tuned if you can wait a bit. I have ordered some parts to construct a variable-speed drive brush-less motor as conceived by Oliver on Vela Nautica - waiting for the parts now. I have been in contact directly with him.
I will start a new thread if I am successful.
Phantom A54 #44