Have you seen the most recent picture of IO? Wait, i don't think that was supposed to be let out of the bag.. shut me mouth!
I wouldn't breed anything to a heifer, unless it was a calving ease Angus, Red Angus, or maybe Maine... i don't like to take chances!
If the cow is s minus on frame size.. I wouldn't use IO from what I have seen of him... To me, in the pictures he didn't look much bigger than a feeder calf