I am not sure on this, so others in the know may shoot me down.
That said, I have a little LPG knowledge.
I have experience with gas, but not in a forced induction situation. ( Impco systems mostly)
My thoughts would be to convert from the complex converter/simple mixer system fitted factory, and change to a simple converter/complex mixer system.
A B2 converter and Gasresearch mixer is a known quantity with blow through LPG systems.
It can be made work very well.
Other people have had great results with Impco mixer and converter systems with forced induction.
I have not done either, but I know a lot of people have with great results.