That, sir, is a thing of beauty.
I'm doing research for a similar build. I've bought a Rabobank C40 with Star threadless fork and am looking to see what to build it with.
The fork is a good dating point. Threadless headsets started to be phased in around 1997-1998. Dura Ace 7700 was introduced in 1997, but most of the Shimano sponsored pros were riding prototype versions by the end of 1996 .
This pic of the '96 Paris-Roubaix sweeping Mapei C40s shows them with steel forks with threaded steerers. It looks like Bortolami and Tafi were using 7410 while Museeuw was on the then prototype 7700.
Here's a pic of the Rabobank C40s from sometime between 2000 and 2002, showing them with star threadless forks and 7700 (or perhaps prototype 7800?):