1. You plan to route 4 housings through the bars & stem using this https://jagwire.com/products/diy-cable-kits/2017road-elite-link-brake-kit? Having routed 4 VB bikes with keb-sl housing (full internal), i really dont think it's possible, so very curious to see how you manage that.
2. If i had extra spacers like that under my stem, i'd probably run an extra long plug expander to spread the forces over the widest possible area. Leverage is a thing, so if you hit a bad pothole, you're at a materially higher chance of cracking the steerer if you run tall chimneys like that. That's also going to add another sharp bend to the routing.
3. so the frame is 1060g and they advertise 950g. Did you ask if the 950 is a raw carbon weight? Primer & paint done by VB is going to add weight, idk if it adds 100g, sounds like a lot, but I'd say >50g. At which point a 50g variance is 5% of the advertised weight, i guess it's within spec? When you order rims, if it weights 460g, the seller typically says +/- 15g, and a rim is a lot less intricate than a frame.
My built is finally finished. At the end I opted for only twoo of largest spcers, one from my extra spacer kit (I know, its the same hight, but less hassle).
When I tried to assemble the handlebar with the 4 cables I quickly gave up the idea of using my used link cables. The thight space in the handlebar lead to gaps between the links, so I ripped it out and used the jagwire road kits instead.
I don't like how velobuild routed the cables underneath the stem. They dont run internally, inside the stem, but underneath of it in a canal. So there is a even tighter bend between the fork and the handlebar. I even had dificulties running the inner cables through the housing when reaching the bend. They got stuck, and I had to loosen the handlebar again.
It would have been better if the cables run inside the stem. They would have more space for the a bend with a biger radius.
It was a big hassle, but at the end everything is working well.
7,8 kg with Sensah Empire pro, onirii/iiipro cable/hydro disc brakes and elite edge wheels.