If it was me (and if that counts for anything), I'd probably look at using a modern turbo, modern ECU and coil on plug set up etc.. there is some really good stuff now for L-engine guru's.
https://www.facebook.com/protunerzz/
And I'd add aircon in the old Z. So you have a nice comfortable street driven Z with modern luxuries like aircon for those hot summer days. But also plenty of power when / if you want it.