Hey scott the NGK catalog says
Recommended plug BP6ES-11 gap plug 1.1 preset
Iridium spark plug BPR6EIX-11 gap plug 1.1 preset
http://www.ngkspark.com.au/sparkplug_cars.php?PageMode=Results&Make=Nissan&Model=280ZX&Year=197919842.8LL28E
I run a L24 ,E88 Head, 280zx dizzy, 10mm top gun leads, MSD 6AL
And i use BPR6E that are V groved and the gap is set at 0.8
Went though heaps of plugs (and different brands) too find the ones that work best (NGK)
Hope this helps Pauly