I have always thought of trying to swap a seagull movement for a Landeron movement in one of the PP reps. The use of a valjoux movement might cause problems in that I believe a V23 is smaller than a seagull or a Landeron movement and I l believe that the sub-dial spacing is incorrect, so you really can't use a gen-spec dial on a seagull/Landeron movement.
I really haven't spend a lot of time assessing this project, because I have yet to run into a PP that I like in the sales section to experiment.
Just a thought...