Ok, to do it so that it isnt too expensive, just do this.
You need to get some custom made pistons, you can get these off the shelf in the UK, or custom made here for around $1200
Use the standard turbo rods
Take our the cams and see if you can get them ground down to a reasonable profile (probably not) to get some new billet cams machined to a good road profile (L1 and F1 is a good start). Dont weld up cams on a YB as I found from experience, along with some others that it ends up destroying the YB buckets.
Put some webbers on it if you like (I have a manifold for YB to webber that would suit), might be worth injecting but it is probably double the cost to do EFI over webbers.
Get some extractors made (I have a spare set of pipes, I think, to suit a n/a YB into a Mk1).
You can use an escort 4 speed and bellhousing if you like. You need to use the YB flywheel, so the clutch will have to be a YB cluth (I think, mine is not standard)
Thats Ill I can think of...
jamie.augustine@motec.com.au