Wow, that would be a real nice present! I would say that the SM025 would be a good model (the smallest you should go)for a large packer brisket. I do a few a year and I have fit a large 20 pounder in there. The racks are 14 x 18. The only thing I can't do is hang long sausages in it, but I have done shorter ones. The original model the smallest one they sell, is 14 x 14 racks and I think that would be too small.
Your friend will be very luck!