The NZR Consulting site currently says 2.85 miles, and finally they now have an illustration you can bring up on their website. The other place is the CIRCUITI site out of Italy (the site is in English also), which has two other proposals on it.
NZR Consulting (Tony Cotmans' track design group):
http://nzrconsulting.com/dev/
The Italian track database:
http://www.gdecarli.it/