Developing show heifers

I am not a show cattle person.  I run commercial cows and a few PB Angus cows and run a small feedlot.  My daughter and a few of her friends have 4-H heifers at my place that are currently weighing 800 lbs in moderate condition.  These are PB Angus april yearlings that have been grown out on haylage, corn silage and a sniff of HM corn.  I need to have these heifers ready for shows from Sept. through Nov.  There are 3 TC Freedoms and a Connealy Onward heifer.  What I was thinking of doing was to turn these heifers out in a small paddock of about 4 acres of orchard grass pasture and feed them all the grain (oats) that they want to eat until July and then repalce 1/2 of the oats with dry corn to feed all they could eat  until show time.  These are good heifers but there is not a big-time heifer amoung them.  I want the girls to go as far as they can with these heifers but realistically you aren't going to see any of them in Denver next January!  What are your thoughts on developing these heifers.

I would feed them a good heifer developing ration( 12% protein 2.5% fat) or just a grower ration and once they start getting to fat feed 1/2 grower 1/4 beet pulp and 1/4 oats. Feed at the rate of about 2.5-3% of their body weight. Then at night turn them out in your 4 acre pasture.