The car is worth about $100,000-$125,000 US dollars done to "club concours" standard, and about $150,000-$175,000 if done to Pebble Beach standard. Figure from there based on what is needed, and how much work you can do yourself...
Translation said:The guru for Freccias is the Belgian Luc Colemont, who wrote a book with a register (see www.frecciadoro.com -- a 2 MB PDF excerpt of the book is available here) and goes by the name of Freccia on AlfaBB.
Furthermore, important contacts seem to be with the 6C2500 Register (especially their historian Gippo Salvetti und the technical advisor und world class restorer Fabio Calligaris).
I think Stu is about right, but could be on the low side. I've seen a car that was an excellent resto project that sold to Russia earlier this year for about USD 65k when the USD was about 10-15% higher.
no 103 was 916.600
no 90 was 916.602