A bit of progress on sourcing the parts. The main thing is that I got most of a SRAM Red 22 groupset. The new aim is the region of 7.7kgs which is pretty realistic with the parts here.
Frame: Paul Hewitt Columbus Niobium Steel Triple Butted
Forks: Easton EC90 SL Carbon fork (might replace with something that can take 28mm tyre)
Wheels: Cero AR30 EVO 30mm, 1390g
Tyres: Conti GP4000IIs 25mm with Schwalbe Extra Light tubes
Chainset: SRAM Red 22 carbon compact, 34/50 with SRAM Team GXP BB
Gear/Brake Levers: SRAM Red DoubleTap 22
F/Mech: SRAM Red 22 Yaw with chain catcher, 83g
R/Mech: SRAM X0 10-speed long cage, 200g
Brake calipers: SRAM Red Aerolink
Cassette: SRAM Force PG1170 11-36
Chain: SRAM PC1130
Seatpost: FSA K-Force carbon 31.6, 25mm setback, 210g
Saddle: GUB Carbon, 154g
Stem: Ritchey WCS 100mm, 109g
Bar: Cannondale Escape Hanger Carbon 44cm, 201g
Headset: Cane Creek IS-2i
Seat clamp: KCNC SC9 Ti bolt, 13g
Pedals: Look Keo Ti