I would think that most places in your area, 60 acres should have adequate forage available for 8 head. However, I know there are always exceptions.
Longhorns are just like any other breed of cattle. If they are underweight, and do not have adequate forage available, then supplementing them some could be your best option. Adequate body condition score is essential this time of year, heading into winter, as the quality of the grass diminishes. You might be able to get by with just supplementing hay, or might look into cubes or some other form of feed.
Also, make sure they are up to date with all vaccinations and deworming. That is very important, too.