I know guys who have messed with A series turbos for over 10 years and at one time they were cranking out 2-3 1200's turboed a week. I remember there backyard at one time had 14 1200's all waiting on the same treatment, These guys got me started on Dattos and turbos and I haven't looked back!
I myself am building an A15 turbo for my 1000 wagon!
The basic setup was as follows:
A- series engine
T3 off a nissan VG20 ( Twin wastegate one)
intercooler
electronic ignition
VL commodore fuel pump
Malpassi fuel regulator
Stock carbie ( modified )
The carbie was modified by resizing the jets
and pressurizing it for boost !
This means the float has to be solid so it doesn't collapse ( brass float is no good)
And the seals on the carbie have to be made better to withstand the boost supplied!
From my friends experiances and i have witnessed this, a stock a series will out perform a modified a series when turboed.
From my own experiances from being in a 1200 a15 turbo and racing a mates 1200 with a stock CA18DET I have seen a turbo a15 out perform a stock ca18det!
Even though my friends have shown me this I am still modifying my A15
Ported head,
double valve springs
larger exhast valves
turbo cam
decomped engine
electronic ignition
fuel injection
and so forth I am not saying mine will go anybetter but i am trying!

I don't see how you could say a CA18DET could be more reliable than a turbo a series if it was injected! ( maybe it is just your experiences with a carbie setup that make you feel this way!)

All this said and done I am only using an A series due to engineering requirements in NSW ( 1000 can only have upto a 1600 turbo engine in NSW without other requirements! and if i was going to put a 1.6 litre engine it would be late model and a Nissan engine and the cost of fitting a rearwheel drive gearbox out ways this option! atleast to me! )

But dude if you are keen I say go for it!

If you got any questions I am only to glad to help you out or aleast tell you what I have experienced with this kind of job!

( If you didnt realise their setup was blow through! Some might say boxing the carbie might be a better setup but I have not tried this setup so I can't comment! But from what I have seen from old factory American setups this could be a good way to go!)