I don't mean to discourage you but:

1. VW has in the last 20 years been driven by availability of engines, not cars.
In 83 (in the US) the hot engine was the 90 hp 1.8 GTi engine. The factory could
not make enough. It took 5 years till any got into salvage yards, in the us
anyway.

2. The 16v engines did the same thing, factory could not make enough, very
scarce in salvage.

3.  TD engines, Same.

All these engines were put into upper, higher cost models and as such were not
likely to be totaled and end up in the salvage pipeline. Now (once again) they
have the TDi engine and the factory can not make enough AND (once again) they
are putting them in the higher priced models which will take a long time to get
into salvage yards.

Many of us would never consider putting $3,000 to $5,000 into a kit for the
engine and parts.

I converted a diesel vanagon to gas with a GTi engine. I bought the Vanagon for
$200 and had the GTi. Very low cost. The days when we can drop by the local junk
yard and pick up a TDi engine are many years away.