I live in garvin county, just a little west of where you want to be. There are alot of differences in land bottom land,up land,improved or native pasture,fertilizer? Are you going to bale hay or buy it? Size of the cows.
Our home place is 160 acres and our best land about 80% creek bottom.If we fertilize good we can run 45-60 pairs depending on the rain we get,but with fertilizer at an all time high it's not cost effective.Our other places have less bottom land and we may only run a cow to 10-12 acres on some years.
I would buy bottom land as you will get the most bang for your buck most of the time.If you need to get rid of some money buy native upland pasture,it may be a good investment and you won't have to fertilize or do much other than keep the fence up.
The noble foundation in Ardmore can give you alot of info.They even have a cumputer program that will tell you how many cows you can run(IMO it has some flaws,but it's a good place to start.)This is a free service so even if you don't like what they say your only out your time.
http://www.noble.org
#(580)-223-5810