teknomage,
You may want to reconsider a VGT turbo, as the IDI diesel is quite dirty and could seize the vanes. This was an issue encountered with the 6.0L powerstroke and it is direct injection.
A ball bearing turbo would give you similar performance to the VGT, with less chance of failure. Personally I like the idea of turbocharging in series (compound), reason being it allows both turbos to operate in their efficiency range and they help to control egt, which is something that needs to be watched closely on a turbo IDI.
I've got a nice air research t3 with a 2.5" V-band outlet housing, internal wastegate I'll probably use as the high pressure turbo, and size a holset from a cummins application for the low pressure turbo.
Low Pressure turbo = big turbo
high pressure turbo = small turbo
Atmosphere
> L.P compressor inlet
> L.P compressor outlet
> H.P. compressor inlet
> H.P compressor outlet
> Intercooler
> Intake
> Combustion chamber
> Exhaust manifold
> H.P Turbine/wastegate inlet
> H.P. Turbine/wastegate outlet
> L.P. Turbine/wastegate inlet
> L.P. Turbine/wastegate outlet
> Exhaust system
Atmosphere
I am still researching to understand the math of compounding, but if I find a suitable engine, then I will be able to experiment as well.