To identify the coordinate system, look for something on the map labelled "Meridian." If there is a legal description, it might name the meridian. In legal descriptions, meridians are sometimes abbreviated, such as "W.M." for Willamette Meridian (covering OR and WA). If the land is in Louisiana, there's a good chance your map uses the Louisiana Meridian. If you can identify the meridian, you should be able to convert your X,Y coordinates to GPS coordinates.
It is west of the Mississippi River so it would be the Louisiana Meridian.
I have a set of X,Y coordinates nearby on my map. Where do I go to find the GPS of that coordinate?
From there I can follow the distances and bearings to get where I need to be.
Is the Meridian coordinates given in feet?
As long as I now the initial point of the system, can I use the coordinates as measurement in feet to the location?
http://en.wikipedia.org/wiki/Public_Land_Survey_System