The set-up you describe would put the t/b's after the blower, is that right?
If you put them in front of the blower theres no point as you would be feeding the airflow through 8 itb/s then one compressor then back to 8 manifold runners.
Assuming you put them after the super/turbocharge there could be a nominal increase in performance I couldn't see it being worth it.
Would you house the ITB's inside the plenum of have the plenum on top of the itb's. If the itb/s are inside the plenum you'll find them impossible (or near enough) to adjust/work on whilst if on top it will be very hard to mount solidly plus how would you hang the blower off it? If running a turbo the mounting is a little easier.
Remember you need to seal the plenum to all 8 itb/s well enough that they do't leak under 15lb of boost.
Lastly as the itb's are after the blower when you tried to shut the throttle the pressure may try to keep it open.
Lastly think of the pressure waves inside the blower as you shut the throttle.
I've never seen or heard of the throttle being placed after a supercharger and probably for those reasons.