Patrick,
Converting the WBX to air-cooled is done in Germany and South America so I
have heard.
It is simple, cut the water jackets off and bolt on 94 mm T1 pistons and
heads.

The stud pattern on the heads needs to be enlarged a tiny amount to fit on
the wider head bolt pattern.  You can bolt a T4 tranny in to the beetle,
transform has drop in, bolt in kits for this.  You can even drop in a five
speed with some fabricating for the front mount and shifter.

The problem is solved the way the T4 engine is mounted into the T1 engine
bay.  Use a 210 mm flywheel from a T4 engine (smaller than the 228 mm
flywheels) and grind the bellhousing out slightly and use a Bus 1.7 to 1.8
starter.

The WBX case is similar to the T1 universal case, but much stronger.  Add a
remote oil cooler, use a sandwich plate under the oil filter.  The stock T1
tin bolts on, use any performance T1 header (One that fits around the oil
filter).  Many T1 engine are pumped up to 2.1L.  Use the stock carb, dual
carbs, dual-dual throat carbs or Digital FI.  You can even add a T1 turbo.

Robert