Well the Zetec is almost certainly what I will do if I ever have to.
I'm going to keep my WBX as long as it doesn't give me serious
headaches, but it really seems to be about the best conversion out there
IMO.  I'd consider doing a TD but AFIK nobody offers a "drop-in" kit
that approaches the completeness of the Bostig kit.

I think some people want to stay "true" to the origins by either keeping
a boxer engine (Subaru) or a VW engine, but IMO the Zetec is certainly
as good if not better than any inline 4 that VW makes, much cheaper, and
much more available.

Allan