Tommo,
I did this conversion on my last coupe.
As Andy has said, i also used a stanza 5 spd and stanza sump with an L20.
I didn't have to mod the sump however.
For the crossmember, I cut the mounts down.
I used r30 skyline engine mounts.
I used a ute diff and a cut down tailshaft. (I didn't know about the auto tailshaft)
let me know if you need anymore info,
cheers
Bruce