Canyon
A Storck 1.1 would just about get in there
I think you could probably get a Cervelo RS in for that
Canyons are lovely
Sabbath very good too and could go custom
Enigma – the one they do in columbus XCR
2.5K the world is proverbially your lobster
Buying off the peg I’d go for Binachi Infinti with Athena 11 speed (its an Italian bike so has to have Campag)
Buying bespoke or custom it would be a tough choice between a Sabbath, the Storck and the Enigma
Custom would see you compromising on kit a little but to be honest the low end Road groupsets like 105, Rival and Centaur are so good anyway that you may as well economise there in favour of decent frame and wheels which will make significantly more difference in the Alps !
De Rosa Neo Primato with Athena 11 for a real nice looking retro build