I had a quick look at the built in camber angle of the two struts, and they looked to be the same (I will check properly when I get the chance) so, with a stock or lowered ride height you should still have neutral or negative camber at the wheels, even if you use the shorter original control arm.

Stock control arms should solve your problem i.e. bring the wheels in by 10 mm each side........ And then wack the stanza ones back in once it has been passed. EDIT:
My 1978 ute lower ball joints have the same bolt spacing (where they attach to the lower control arm) as the stanza- Trapezium shape, from bolt centre to bolt centre 52mm at the outer, 30mm at the inner and 28mm on the side. Earlier models may be different.

As for rims, I just asked today +2" rule applies to diameter & + 1" to width, you need engineering approval for more than that (in western Australia). I'm spewing cos 195/50/15's are only give you a 5% speedo error, compared to the 155/80/12's that are on it. (and the speedo reads high anyway, so it would improve the accuracy)

I am pretty sure my stock rims are 5" not 4.5" EDIT: no dammit, I was measuring from the outer edges rather than inner face!

Can you post up more details of the 20V conversion? they're a good engine and suit the car well I reckon (apart from the toyota badge)