The angle of the shackle plays a big deal in the effective spring rate, therefore ride and load capacity. The more it leans forward at ride height, the easier it will be to compress the spring as the load will use the angle to stretch the spring as well as the load compresses it.. meaning softer compression/less weight carrying capacity.
In regards to extension, you want your shackle to stop short of pointing straight into the springs by a safe margin to ensure they can't flip and lock up forward, or restrict extension.
It would be fine if it was more vertical or even leaned back a little. So from this point I'd be more interested in the ride height and compressed angles. I wouldn't want to see more than 45degrees forward at full compressed.