The Iron Lung Cummins used a Roots style blower (similiar to the one the 2 stroke Detroits use) and the torque rise had to have been something else because there is no lag whatsoever. Max boost hit from just off idle, which is what we want on a diesel when we are pulling. The centrifugal blower will have a more gradual boost curve, which would be good for an IDI since max pressure will happen later. This takes the load off the motor at low rpm, since it is high cylinder pressure at low rpm that kills the head gaskets, pistons and rods.
Just as an aside, there is a Whipple screw compressor kit available for the 6.5 GM IDI diesel and if they can do it on an engine that is not as structurally strong as the 6.9/7.3 IH your engine won't be a problem. They have it available for the Hummers and marine applications.
The main thing with boosting any IDI style motor that was not initially blown is dealing with the high static compression ratio. Diesels can suffer abnormal combustion just like a gasser (that's where the rattle comes from anyway), it's just that we take advantage of it. The DI motors like the PSD, Cummins, and DMax only have 16-17 to 1 compression, so the preboost pressure in the cylinder is much less. Now compare that to 20-23 to 1 compression of a NA IDI motor (the 5.7 Olds was on the high end and that with the weak head bolts, head gaskets and no water/fuel seperator killed it) and you can see how things can go bad really quick.
The tune is everything, and with a stock compression IDI it is very critical. As much as we like to emphasize higher fuel rates and boost, it's really all in the timing. Get the timing wrong and stuff breaks.
This project you have is part of a trend that I've been seeing and I wish you well. Shade Tree Conversions (they advertise here on this site) has a Vortech supercharged Perkins in a Ford F150; give them a call about it so you can get some info about what it's performance is like.
