HI,
Over here in the USA the Bentley manual is the bible of VW repairs. I know you have it over there also.
Most of the dimensions you desire will be in the book, It is interesting that VW never published main bearing to Journal clearances.
What they did was describe what is basically a "feel" test about the amount of resistance it takes to rotate the crank after reassembly.
If you are rebuilding the engine, the Bentley will be a great resource for that as well as virtually any other repair you make on the car.
What year are you working on?
The Bentley manual varies in cost here depending upon the year spread it covers. They average about $100 US, expensive but worth every penny.
You are spending a lot of money to rebuild the engine, an additional $100 is money very well invested to make sure it comes out properly and runs for many thousands of miles.
I will stress that you reinstall every piece of tin you took off, especially under the cylinders on each side is a small insignificant looking piece that is critically important to proper cooling and hard to put on later if you should forget it.
As an additional reference
www.thesamba.com
is a great forum, information and product source. While based in the US it has members from around the English Speaking World. (and some that don't speak such good English)
Dave
"If you don't have the time to do it right the first time, when will you find the time to do it over again later?"