The runners are admittedly on the short side with the Cosworth design, and those curve DOWN slightly, which adds maybe 10-15mm to the length. If I tried to recreate it with straight runners, the distance from velocity stack to flange would probably be 6" or less.
I went way down the rabbit hole on intake runner length last time, and I think I was able find a decent compromise with the last manifold. This time, with less room, I will need to make concessions. The plus side about shorter runners, is that I wouldn't mind revving this thing out. 8k with lighter pistons and rods seems reasonable, and my new turbine housing should flow up there. So maybe if the manifold ends up with short runners, I look at some cams and fueling to support a higher revving, less-of-a-torque-monster engine.