Well when I was researching all the transmission firms I asked where warning me I might have problems so that was as far as I took it oh & they wanted silly money to do it.

I do build my own boxes so I could probably do the same as you.

But after researching these front diffs, they seem perfect.

I have stripped & rebuilt one, it's really good quality, just seems the right thing to do.
They have been run on a car for almost 10 years at up to just over 600bhp/550lbs with no problems & appear to have no issues.
So I know the reliability is there.
They are cheap for what they are & I have the matching rear diffs.

Everything is in place I just have to tell the company to make them.

It would be silly of me to back track now but to be honest you are probably right about the Skyline box, I have one here but I have never rebuilt one