Does it have to be an ABV 2.9? It might be easier to get everything thing from a mk3 so you know everything will be plug and play I.e any wiring looms you may need ect
If the ABV engine isn't running a coil pack you'll have to get a AAA coil pack upper timing chain cover and swap them. I think the odb2 inlet is different to the odb1. I got just a bare ABV block and swapped all my AAA odb2 stuff onto the ABV lump