Found some good info from Schroth on harness mounting specifics:
http://www.hmsmotorsport.com/docs/Co...structions.pdf
As far as shoulder harness angles, downward up to 20 degrees is okay.
For distance from seat back to shoulder harness points: Webbing should be crossed if the distance from the seat openings to the mounting bolt point or harness bar exceeds 450 mm (18”).
When mounting to a harness bar with a wrap mount and the distance to the bar from the seat is less than 450 mm (18”), a section of roll bar padding, fixed with cable ties, should be added to the outside of each of the shoulder harnesses to ensure that they can not further separate when unloaded.