Why didn't you put the top rear shockabsorber mounts above the centre of the diff. They say you can gain more wheel travel that way.
Mine go straight up to high mounts.

I still have 780mm of flex at the back

So you can see it is not restricting wheel travel that much . So what is the advantage of straight up ?
There is a big advantage because it gives a lot more stability on the road . I can go through most corners at a 100 kph without body roll.
If a spring goes up 150mm and then drops 150mm the shock compresses and expands 300mm with it in a vertical position.
If is over the diff in the middle it only moves 200mm + or - so the shock is nowhere near as effective there fore resulting in body roll and wallowing on the road.
The main thing is to have shocks that have very little shocking up and most of it down so the wheel then easily climbs over obstacles off road.
cheer Richard