Sounds like an interesting and different project. Just a few pointers that will help you:

HJ sedan diff won't fit. You'll need a HQ-WB V8 housing and swap the internals over. No need for rear disc brakes either, the WB drums should be more than good enough for the chassis' capabilities.
Stock black motor rods and crank are cast not forged steel.
You might find it hard to Engineer and hence pass rego a blown 202 in a WB. The stock VK EFI will be a snack as WB and VK are the same vintage, but a blower may complicate it to the point of not being registerable. What would easily pass though (although you have said you don't want a V8) is a 5.7L/350ci engine out of a HSV - basically a 304/308 stroker, and is as easy to fit as a VK EFI 202 is. In stock guise this should be a snack to Engineer and would probably be cheaper than building up a blown 202 if you get a good used engine and probably have more power. As would a blown V6 out of a VS or VT, bit more to fit though as it needs specialty parts whereas the Holden V8 will bolt straight in using 253/308 sump, pickup etc.