okay, doing some research for blow through carbs for an a12 set up, the kb laser option seems do able with no change to the needle due to the increased boost being put through the a12. It may run a little rich, but better than running lean if you get my drift (bang!).It is off a 1.5lt engine so would be ideal for a a15, it produced 75kw in standard form with some mods it was limited to 90kw, by design limitations i believe. And only approx 500 made it to AUSTRALIA.
Who said they fit an a series inlet manifold with one more hole drilled in them? i would like some more info.
Another option would be from a gh sigma turbo, a 2.0 lt engine so maybe a bit big, but cant find enough info yet. But more sigma turbos than kb laser turbos running around.

I think it is me you are refering too!
Firstly I said Non turbo KB laser carbies are the same as 1200 and so on ( just a later version " Hitachi" )
Never seen a factory Turbo KB laser but asuming they have the same carbie this will have relivence!
( I do know of a non turbo kb laser which was turbo charged but because of the boost pressures it ran it to needed the carbie to be modified for boost!)
We found near or over 15psi boost for either laser or datsun carbies required them to be modified for boost!

Also this turboed lazer had a datsun carbie throtle plate ( the throttle body of the carbie!) fitted to it as lasers only had vacuum secondaries!( maybe some lasers do have mechanical secondaries! but I am not sure!)

Anyway I fitted a kb laser carbie to a N/A 1200 as the datsun carbie was Rooted and the KB is all we had around at the time!

I will post a pic today of the mods required to fit it to the datsun manifold!
I will put it under " forum" "Carbie base Plate"

one other thing is that never did we require any changing of the needle and seat for boosting our setups!
Only things were float was changed to solid plastic if it wasn't already!
Secondaries jet was drilled to the size off a 3 litre commodore jet and for hi boost the carbies needed to be sealed better!

Can you find out and let us know what was used on the KB laser turbos ( factory)
regarding fuel pumps and pressure as this is a major factor! ( limiting the amount of boost able to be applied to the system before leaning out!)

Cheers Steve

rumor has it that theres a weber down draught carb setup for blow throu turbo on an alfa not sure what model will make more inqurys