Typically, it's not practical to take a 100mm hub down to 90mm. That means removing 5mm from each side, which is a lot. On a Campagnolo hub (road or track), you would have to totally eliminate the locknuts and lockwashers to achieve this reduction. Seeking out narrower cones is also not practical, as you will lose access to the cone adjusting flats and could end up with an incompatible race profile that will accelerate wear.

I really think the most practical solution is to cold set the blades. Spreading them 10mm should not be a problem. Alternatively, you seek out a quality hub with narrower spacing, but that may take some time.