http://www.vectronicsappleworld.com/collection/maciisi.html shows the Nubus adapter mounted with the Daystar adapter -



As you can see the Nubus slot points straight at the Daystar accelerator. Even without an accelerator in the lower slot, the Nubus slot points straight down at the motherboard. Something along the way, probably more than one thing, would have to be right angled to make it possible, even barring case issues.