I hunt in the sandhills of SC and our soil is very poor.  It is pine tree country and the soil is also very acidic.  I was wondering how LabLab would od in this planting situation.  I have limed and fertilized to a extent, but have to budget what I put into it.  Any info would be greatly appreciated.

The size of your plot is going to be a determining factor of WHAT to plant.  Meaning, it may be fruitless to plant a half acre of Lablab, as this may get grazed off prematurely.  If your soils are sandy, you may want to consider Alfafeast(alfalfa, clover, chicory mix) but the PH will most definitely need increasing. 
The problem with sandy soils, as you may well know, is getting the root system to establish well before periods of dry heat.  Sandy soils drain extremely fast and can be troublesome.  Alfafeast would probably be your best bet in that situation but the PH is going to play the biggest role outside of fertility. 

Fall annuals might be your best bet.