First off, do not use Dr.Who. I use him on cows and get 90-110 pound SQUARE calves. Which leads me to point #2.
It is not the weight of the calf but more importantly the SHAPE. Just remember: Round hole, square peg rarely works. Which leads me to point #3.
Why not angus? Your whole purpose of having heifers is to developing them into cows. They can not do that if they die having their first calf. Or if you have to do a c-section or a hard pull and ruin their reproductive tract. The goal of a producer with heifers is to have them have a LIVE calf, on their own, and milk well enough to raise it, AND get bred back.
If you are concerned with angus not being showy enough, try using Juneau, or TC Freedom, or MaxiHB40. Legend has been used heavily in clubbie herds with good luck. I didn't have luck with him, but a lot of others love him.
If you just refuse to use angus (and that is just silly) and you want your heifers to become cows, look hard at Jakes Proud Jazz.