You could use the clutch & flywheel from a CA18DET but you might have to also use the RS5F50A (or V) gearbox, as it may not fit in the RS5F31A bell housing.
The 50 series box would most easily be obtained from a CA20 powered Bluebird U12. 4WD versions were used in GTiR, U12 & U13 bluebirds. Front wheel drive versions were in U12 & U13, and Maxima/Cefiro.
It will mean some mucking about with CV's, mounts, speedo & selector linkage. Have experienced this fitting into an N14, all dooable.