I would suggest that as long as you don't mix types of fabrid within a quilt, it should be fine. I have seen lots of poly blend quilts that turn out fine, even poly knits (yuck). It depends on if you want to make a quilt for showmanship or function. There are so many needy folks that would be happy for anything.If you have that much fabric, you could surely find combo's of color that look great together.
Once I had 4 big black garbage bags full of various knits. I made them into 14 large quilts (similar to a blizzard quilt) to send them to disaster folks (can't remember which disaster it was, but I do remember it was a cold climate. I never saw the faces of those who received them, but I could feel the happiness in my heart. They actually were kinda pretty!