Although slightly rarer, the ABF also appeared in the Ibiza Cupra GTi 16v and Toledo of the same era so worth keeping an eye out for one of those too.
An ABF goes for between £0 and £300 these days - more likely to go up as they get scarcer (try finding a 9A for reasonable money!). If it were me I would buy the ABF+loom - for no more than £400 - and get the conversion done with that engine. Meanwhile, source a spare ABF and get that rebuilt.
Whilst the donor car route is a viable option, I personally don't have the space for one - or the energy to strip one down