The wider track and more camber on the rear is caused by the rear arms. The plate that is welded to the arms where the hubs mount are a bit thicker on the Granada to give the wider track. They are also under a slightly different angle to give more camber, which is done because of the higher standard ride height of the Granada vs. the Sierra.

I have put the front Granada and Sierra arbs directly on top of each other and they are the exact same length on the Granada and Sierra, it's only that the Granada arb is a bit wider because the tcas are longer. But using a Granada arb on a Sierra will still put the tcas in the same location.

@Damo, I remember you saying in the past you had machined the Granada arb to move the tca a bit back so the wheels would sit more backwards in the wheelarch. I think that must have been because you are using Granada hubs instead of Sierra hubs. In the past I have also used a Granada arb with Granada tcas on a Sierra and it was fine. I even put a few washers in between the arb and tca to give more caster. Did you change the machined 29 mm Granada arb for a standard 28 mm Sierra arb? I assume this cured a bit of understeer? The thinner front arb will more front end grip and if it's not machined anymore it will give more caster which will also give more front end grip.

TBH I wouldn't use Granada front hubs on a Sierra. I have the feeling the put the wheels too much to the front and give a too low front roll centre, because of the higher standard ride height of the Granada vs. the Sierra.

The 3dr hubs would be best, but they are difficult to find/expensive. I thick the 4x4 cos front hubs would also give a good front setup when used with a 2wd crossmember and 2wd arb, but these hubs will push the brakes quite far outwards giving possible problems with wheel clearance.