Yes, seeing as it's an L8 set-up connect the tach. wire directly onto pin 7 of the ign. amp, i did it on my non cos. turbo 16v twin cam 2.0 engine and it workes perfectly with the stock car ins. cluster's rev counter.
I wouldn't be too sure that it'd generate a proper signal for the shift light seeing as the amp. is also connected to the coil, try it out anyhow.
Let me know if it goes ok.