I'm not sure it will be considerably stronger. Alloy axles will be an improvement, but those can be stock alloys as well. 14 bolt hubs are stupid strong. The cruiser pinion isn't.
IMHO, if you want strong, just run the entire 14 bolt

They can be found super cheap to free.. And I think Axle Craft makes the sleeve kits to use two short side shafts. And obviously run his 6 lug hubs as well.
I just don't see a major reason to spend that amount of money on a toyota axle. It won't be that strong in 30 spline even with upgraded shafts. Kinda like the guys that upgraded the heck out of their D30 axles in Jeeps. It did nto take long before they replaced them with stronger units.
SOR says they have the 40 and 60 series FF axles in stock currently.