Turbo mount is completely different. You probably couldn't even get it to mount without some serious custom fabricating. Block, manifolds, up pipes, IC
plumbing, downpipe, etc... would all be custom. You might be able to use some parts off a 7.3, but not many.
Spooling a 7.3 turbo on a 6L is going to suck without a really tight housing. It's all about the mass flow rate.
The mass (matter, be it exhaust, fuel, air, etc...) is what drives the turbo. The lower displacement of the 6l means two basic things:
1. The amount of fuel / revolution to make XXXXrpm is lower than on the 7.3L.
2. The amount of air / revolution to make XXXXrpm is lower than on the 7.3L.
Combine these two things, and you see that the GT(P) 38 will not be spooled until a much higher RPM on the 6l than the 7.3.
A 'good' set of injectors won't help. All it will do is put more fuel in. Without air, all you have is a bunch of smoke and no power.