Surprise.....it's an R180 fitted from the factory for this special base model 280ZX. No wonder the factory clutch had to be returned ...twice! It's an old Datsun 810 clutch part number! Now that the diff. cover has been scrubbed it's pretty shiny.
Went with 42's and a TWM manifold. Still lots to sort out, but Ill start another thread on it somewhere and link it back here. Rought calculations hopefully put it in between an OER setup and a Mikuni PHH setup $wise.
Part of running a single shared throttle shaft was for a super clean look- like how datsun_tokyo linked above has it.
I also still haven’t decided on the manifold- but was planning on the TWM one- seems to be the cleanest and allows me to run without all the linkages.