First you need an ECU. I recommend the 550. Even if you don't need all of the inputs currently, you probably will find a use for them in the future. And I build the wiring harness from scratch.
FT550 with no harnessI also recommend the NanoPRO over the plain Nano. It adds a bit of functionality and a couple of more display options. And this harness is a bit much to make myself, so get one of those.
NanoPPROA SparkPRO-4 is needed if you want to run OEM stick coils. This is the cleanest packaging ignition option. Just get the connector, not the full harness.
SparkPRO-4 with connectorThe MSD solid state relay bank is the single best electrical upgrade to my bike in 2 decades, other than the FT550. Cleans up the wiring but, more importantly, makes troubleshooting voltage issues a breeze.
MSD Solid State 4 Bank RelayThis is the basic sensor suite that I run. Higher pressure sensors are the same price, so I only carry a 300 psi spare.
Oxygen sensorI use OEM sensors for block temperature and intake air temperature and they work fine