If you would like to email me your block and lot and what town your in, I'd be happy to look up the applicable zoning ordinance and let you know what uses would be permitted as well as what other improvements may be required by converting to an office use. As a Engineer and Planner in NJ I deal with zoning regulations all the time. I can also describe the process to get the office use approved by your local Zoning Board.
You can email me here: joe@landmanNJ.com
Joseph A. Mancini
AVALAR Atlantic Properties