I'm in the process of going turbo on an M10 and from my research, the Bosch L Jetronic injection from an mid 1980's 318i is the better option. It has a fuel rail and injectors that mount into the intake runners. Since you will most likely have to increase the amount of fuel to feed the turbo , this system is more adaptable . The original 1974 and 75 2002 turbos had compression ratios of 6.9 to 1. Your rebuilt engine is undoubtedly higher, so don't plan on applying boost of more than 8 lbs by means of a wastegate
Going to fuel injection and a turbo is no simple matter and requires complete electronic engine management
Done well, you can expect to have 180 HP that is durable and reliable
Other things to consider:
More Cooling both water and oil
More brakes , and
More suspension
I'm not Familiar with an Emerald ecu, but be sure it offers everything you need. You should have a trigger wheel ignition , a second signal from the distributor drive to act as a cam sensor to control sequential fuel injection, an oxygen sensor to control A/F ratio, and a Vacuum/ Boost control of the ignition curve at the least.
Best Regards