You are not completely off base. But you may not have a complete understanding of the Spica system. It uses injectors, not jets, and those injectors are fed by a 450 psi pump, which is fed by a ~30 psi pump. You can use megasquirt: you remove both pumps, and all the injectors, because they are not electronic. You have to adapt the Spica manifold to accept electronic injectors and fuel rail. You install your EFI pump of the 45 - 50 psi variety, wire the injectors to the megasquirt, a few other minor things, and yes, you have a Spica manifold and a megasquirt system.
Several poeple have done it. Some will modify your Spica manifold to work. There are some posts on this site if you do a search. I want to do it one day, so I've read a lot about it.
I'm not so sure if ITB and turbos go together though. Maybe someone else can comment. I had thought that control of the flow by ITB is moot since there is so much air pressure. Please correct me if I'm wrong with this last part.
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