Just because an animal has both eyes facing forward doesn't mean they are 90 degrees.Al bears and predators that I'm aware of have an angle to their eyes.If you mount them square,the rear corner of the eye will be way forward of where it should be.
When the Buckeye guys studied and measured 150 or so black bears to make their line of bear forms,they came up with an average angle of 72 degrees.I'm positive every animal can't be exactly the same.the best we can hope for is to choose an angle that pleases us and make both eyes the same.
If you make them 90 degrees,they will look cross eyed.
If you buy a quality,commercial mannikin,I wouldn't change anything without my own personal measurements,reference and data to back up what I'm doing.
