Hi, I don't mean to be curt/short in my answer. Here's some of the data.....
1. 016 transaxle can be had for typically $200-300 bucks from auto parts recyclers.
2. fab work I will do myself, will use a cable operated gear change, these are typcally $200-300 bucks, GT40s folks use lots of these and there's always a few available with the right brackets for an 016.
3. adapter plate - this takes some work, but the 016 side is easily available, just not sure about the Lotus 4cyl side. Also, what's the clutch pack, etc. Some research necessary here.
4. engine mounts, not difficult, adapt the audi mountings.
Additional work I will have to do myself because I have an '88 with the inboard brakes....folks with '89+ cars don't need to mess with that. Wish I had an 89+ car.
Net, it's not a lot of cost if one can do some basic fab work. And, in the end, an 016 with a LSD from a 944 turbo is a very solid transaxle.
Just my $.02. Of course, results may vary......