There are some decent buck in that area. I would say 160-170 would be a good goal, but there is the possibility of one bigger. I believe your brother's tag is for any deer, including whitetail, which he has just as good of chance getting a trophy as with the mule deer. The main problem is the fact that it is 100% private land (I believe). So unless you have a good connection, it can be hard to find a place to hunt as most of it is posted pretty hard and lots of the landowners are fed up with hunters, which I can understand with the disrespect I have seen out and about.
Anyway, there is a chance for either species in that area, so good luck.