If you are looking for a high B&C scoring buck, then look for mass, mass, more mass, and then look at the length of the prongs. You will make most of your score on the four mass measurements that go up each horn. Height looks good, but is overrated. The difference between a 14 inch buck and a 16 inch buck is only 4 points. One extra inch of circumference (mass) that carries its way up is worth as much as 6 to 8 points.
That I can see, the location of the prong in relation to the ears has little, or nothing, to do with the overall B&C score (there will always be 2 mass measurements below the prong and two above it). I have seen many goats with low forks (even below the ears) that scored very well, including one a co-workers' wife shot that scored 91. Not saying that, as a general rule, a high prong junction isn't a good sign. It usually indicates a mature and a tall buck, but as far as being a mark of a high B&C score, there are better indicators.
I have a system that I use for judging the quality of pronghorn bucks, but I think I will post it as a separate post (coming soon). Ultimately, what matters is that you pick a buck that makes you happy. An exceptionally tall buck, one with really nice cutters, or one with some unique bumps or double prongs will look much more impressive than a 'typical book' buck.
Here's a tip... If in your minds eye you can straighten out an antelopes horn and compare it to it's face, the straight line length from the tip of the nose to the back of the head is consistently close to 15 inches.
Have fun.