I'm not familiar with those quivers and don't own an ILF bow so I'll take a stab and this may or may not help.
I have a few bows that take a bolt on quiver.Generally,there isn't a lot of flexibility in wood riser bows as to where the two inserts go in the riser.I too like my arrows angled back at the fletched ends.I like the nock of my front arrow just at,or behind the bottom to of my bow.
First I load the quiver up with arrows and hold it to the bow at the angle I want.If I cant bend or alter the lower bracket on the quiver to get the angle I need,I make a longer,custom bracket.
Maybe you have the option of drilling one or two new holes for the angle you need? Or maybe you can customize your brackets.