i don't do turbo motors, but have you seen the SPFI set ups?
a simple way to do forced induction on Subaru's is to install an SPFI injector in the intake manifold just past the throttle body. the idea is to keep stock FI so that's simple and requires no wiring work, but add more fuel as boost kicks in with a dedicated injector. i think it's controlled with a rising rate Fuel Pressure Regulator that increases as boost increases, or something like that. it's simple and parts can be had at yards for pocket change. and you can probably spif it up if you want to.
if the EJ22 intake manifold bolts up to the EJ205 heads, or the EJ22 intake wiring can be fitted to the EJ205 intake manifold, then you simply retain your stock EJ22 control (which is the singular coil pack you want) and add an injector with simple controller (RRFPR - rising rate fuel pressure regulator) or there's probably other options too.
a $200 EJ205 sounds scary if money is an issue, but hopefully you knew the person, got lucky, or stole it, LOL j/k