All the manual d- series boxes are interchangable. The slave cylinder and starters can vary depending which model it came out of. I’ve got a gearbox out an ek civic in mine
Yes I’ve got leathers in mine with a three point centre. I pulled them out a 99 mb saloon, the rear seats are all physically the same size but the rear tilt locks differ, think there’s 3x different types depending on year.
Rough around the edges but a replacement for my old 5 door 1.4i s. Swapped in a d15b after my girlfriend blew the d15z6 up. Rebuilt most of the suspension and welded up the sills over lockdown last year. Great workhorse of a car
Have you considered just a gearbox swap? The d15z3 comes with a very long geared box for economy (3.7 final drive) swapping to one with a 4.437 short gear will help acceleration loads but the tradeoff is higher revs cruising on the motorway. You could stick a d16z6 in but without a short box it probably wont feel much quicker.
otherwise it’s whatever you want realy b or k swap