70-80? Looking at the above picture (the MSA standards one). Side view of the seat, if the bar was exactly horizontal in the middle of the preffered range, that is 0 degrees yes? Well this example is slightly higher than the 0 mark, but within the 10 degrees tolerance, and still in the preffered range. Like your picture posted is not horizontal either, but still within the 10 degree tolerance but the other way.
They would wrap around the bar. They will not slide about as the x part will secure stop one sliding, and the other strap is stopped by the lug near the window side
You completely missed my point I'm not on about the height of the bar