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Astromic.
Maybe I can help you, dont know it its too late. We have a lot of experience with turbos in Brazil.
Let me just tell you what I think and learned through the years.
Blow through - forget the other way, people used draw systems in the past because of fuel starvation, not a problem with todays pumps/regulators.
The modifications you need on a Weber 40 are minimal, and include the use of a larger float needle (300 or 3mm is needed for roughly 300hp on gasoline) and the elimination of the manual accelerator (you remove the whole system and block it off with a little aluminum plate) that's it.
You will need a pressure dependant fuel regulator (one that will rise fuel pressure along with the rise in boost).
You need low CR (I would keep it at 7, or closest to that) and maximum total advance of 24 degrees (depending on the amount of heat you get where you live).
As for the pump, you need a high pressure pump (say 45psi minimum) or in other words a fuel injection pump that flows about 3 or 4 liters per minute.
Maximum boost depends on the engine you have as well as the size of turbo (compressor housing and wheel) but on a small turbo in a stock engine for starters, you would probably be safe to about 15 psi, everything being correct maybe 20 or 25 (we've ran 30 psi on a stock alcohol fed 1600 with dual 44, good for 300whp!!).
Rule of thumb, up to 5 psi even if everything is wrong you are still safe, 10psi is very forgiving, highr boost pressure is when you really start to need to know what you are doing not to start loosing pieces (again this is depending on turbo size since 5psi of boost from a 62mm wheel on a .70A/R compressor is a lot more air than a 42mm wheel on a .42A/R compressor running the same 5psi).
Anyhow, if I can help you further, let me know, I'll walk you through the carb/pump/regulator setup if you wish.
Best regards to all.
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