My root issue is that I have elevation values in NGVD 1929 that need to be related to a DEM which has elevation values in NAVD 1988.
Is there a way that I can convert elevation from one data to another en masse?
I have searched online for a solution but so far have only come up with an app that will give you the difference between the two elevations at a single point.
NOAA distributes an application called VDatum which will do vertical datum transformations. VDatum is free and cross platform but it is a Java application so you will need to install Java. VDatum accepts an ASCII text file so you can do the transformations in bulk. You will need to populate your attribute table with X, Y, and Z values and then export the table to ASCII before feeding it into VDatum.
The links above point to the VDatum download page and the ASCII instruction help page.
