maybe I should take the time to sit down and write something up properly, cause this comes up pretty regularly.

Stanza x-member doesn't bolt-in. I didn't use the Stanza x-member, just picked the saddles off it and welded them on the 1200 x-member.

I had a custom tailshaft made with strong, cheap, and readily available Ford unis.

I used a 120Y borg warner diff initially. They are easily strong enough for the job. I now use the same series BW diff, but the wider housing and lower ratio available in 70's vintage Corollas, using the 120Y yoke/flange.

Hydraulic clutch conversion is fairly straightforward. Just remember to brace the firewall with a stell plate as well where the master cylinder mounts.

I'll answer any other specific questions you've got, but here's some other threads with L series info from as recently as last week to get you started:
I might be picking up an engineless 1200
200B parts into a 1200 coupe

DVLDAT, I know there are some old threads discussing the 120Y L series swap. I can't find them, but there's a couple of pics from when I did the swap here

Het Mat - it's never too late...