I wouldn't even touch the std ECU...
Get yourself an aftermarket one (Hawk, Wolf, EMS, Haltech, MoTeC, etc, etc) & wire that in.
You will also need:
Low Pressure Lift Pump (Carter, Holly Blue).
Hi Pressure EFi Pump (Bosch 044)
Surge tank.
Sump modded with a Dash fitting for the oil return line from the turbo.
Fuel Pressure Regulator (might be able to use the std L28e one).
That's probably all you'll need if you’re doing it on a tight budget.
BTW no one does Turbo kits for L series engines anymore.
You might be able to find some obscure kit in Japan/US, but I doubt it...