Centering new rearend ?

Hey all,

I'm currently building a Ford 9" for my '72 Scamp and am really struggling with how to set the housing up. My wife is using the Scamp as a daily driver, so I can't pull the current 7.25 to check measurements.

I'm aware that factory is 43" between spring perches, so that's easy. I also know the overall width I want between the drum brakes (57 1/8 factory, so I'm chasing 55 1/8). I'm really struggling with where the pinion centreline should be in relation to the spring perches etc. The Ford diff has it dead centre between the perches currently.

1967 'cuda says above that the Mopar pinion is offset to the passenger side by 2.5 inches. Can someone confirm that measurement for later A-bodies?

Would really appreciate some advice on this.

ValiantHardtop,
As I stated, I thought it was odd. So, I'd really appreciate if others could see if they get the same measurements that I did too.