Your saying she is bred this way already? I have had my heifers pelvic measured. My heifers this year project 89# range. I used calving ease bull. I have fed protein blocks and fed grain and fed nothing but hay. Where we are, it tends to be the summer/fall pastures and our winter temps that contribute to birthweights. The worst birthweights when I fed protien tubs and grass mix hay. We only feed hay now unless we have one that gets pushed back and we will supplement them small amounts off to themselves. I have one cow that is consistently fat year round, no one knows when she calves because she looks the same befroe and after. Just a knee jerk response to the mating due to past experience. But you know your herd management practices and what you are comfortable with. You ask what we thought of the mating-just wouldn't be my first pick for this gal.
Never heard of "bloomer" and not sure which cash you are talking about. There is a Cash clubby x shorthorn bred. Carnac son-hope not that Cash. Bloomer I would have to dig deeper.