As said above you need fuel enrichment method,
The easiest one is to swap your injectors with a bigger ones this won’t be ideal but still better than nothing, another easy way is to put FMU right after the FPR this method can work with low boost but like the bigger injectors idea it’s not perfect. I think it could work well on your car with HFM ecu if you only running low boost.

A better idea is to put extra injectors (maybe 2) controlled by device beside your PCM (like splitsecond which seems popular here, you can also use megasquirt as an extra injector controller), what it needs is a RPM signal and manifold pressure reading.
Another good idea is to install a piggyback ecu to just control your existence injectors (like AEM).
Or have a programmable ECU to control only the injectors (Fuel only), similar to the piggyback ecu idea.
To get a good AFR reading you don’t need a dyno, a wideband oxygen sensor can give you that.

The right way for getting all Force induction potential is to control both the FUEL and IGNITION, with ignition control you can get real power gain, with piggyback use for fuel and spark, or fully programmable ecu (like megasquirt, VEMS,Link, haltech,etc….)

A basic turbo kit sould include:
1-Turbo (suitable for your engine and your power goals)
2-turbo Exhaust manifold or adapter for turbo.
3- Wastegate to control boost (external or internal)
4- Oil pressure line and Oil drain line to the sump
5- Intake plumping and intercooler
6- A way to fuel enrichment.

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W123 - M111+Turbo