In keeping with my light restomod idea (restored on what you can see - exterior and interior, and modified what you can’t see - engine bay and mechanical), and now the retrosound stereo is about to go in. It has Bluetooth and Apple CarPlay but is similar to the original
Nissan used very soft oil control rings in the pistons.
These wear first causing oil to be sucked up into the combustion chamber, hence your blue smoke.
Only way to fix it is to rebuild the engine.
Black smoke is an overly rich mixture from those horrible flat top Hitachi's that you CAN'T tune out.
I suggest fitting 240Z Hitachi's or triple carbs.