8 years ago we had an article called "How to fit L16, L18 and L20b engines" but that seems to have dissapeared...
L20b into a Datsun 1200
but there's still some useful info in that thread and the others linked from there.

here's a x-member pic from the conversion I did back in the mid 90s using Stanza saddles on the 1200 x-member, which seems to be the popular way to go these days... I also cut and shut the centre of the x-member and moved it back about 1/2-3/4" to get the motor as low and far back as possible. that's not really neccesary though.






I'd use the BW68 from Aus 120Y sedans instead of the H165. Cheaper, easier to find and stronger.

The Stanza 63a 5spd is the same length as the R30 Stumpy box but smaller in width/diameter and a better fit in the manual tunnel. They're cheap too. Shouldn't be any problem getting 20mm clearance with that box.