If you want a Fuso in a crew cab 4x4, they are relatively easy to convert. The key is to start with a 2WD truck, which uses the Aisin 68RC transmission from the Dodge 3500 chassis cab. After changing the tail shaft to a 4WD housing, the factory Dodge or any number of aftermarket transfer cases will simply bolt up to the Fuso transmission. This also eliminates the stupid Duonic design found in the USDM Canter FG.
If you wish to keep the Fuso rear axle, different wheels will be neeed back to front. A Chevy D60 fits quite well under the front of these trucks, as does a Ford Superduty D60, though more lift is required with the latter to clear the diff.
Any competent 4WD shop should be able to perform the conversion. Factory NPR springs will bolt to the GM D60, I am not sure about the Canter springs. This leaves you with OEM parts throughout the truck, i.e. nothing is custom fabricated or $$$$ parts. Hardware should run in the 5-7K range depending on your parts selection.
There is a company in Florida that will convert Isuzu NPR double cabs to 4WD for about 10 grand, drive in, drive out in 3-4 days. The conversion is not difficult to do DIY, with some experience and the proper tools. I haven't a clue what a 4WD shop would charge to do it, but being in California, you should have no trouble finding one to do the job.