Hello Jennifer, welcome to the forum.
Yes you have the unit right, the 2751st Heavy Shop Company has a Campaign Credit for the Western Pacific, and a Meritorious Unit Commendation for 2 March - 2 Sept 45.
An Engineer Heavy Shop Company consisted of 6 officers and 165 enlisted men.
A semi-mobile unit, the heavy shop company performed fourth echelon maintenance on all equipment for which the Corps of Engineers had maintenance responsibility. Fourth echelon maintenance included rebuilding a units equipment, overhauling the the attachments and accessories, doing emergency overhaul of major units, and recovering equipment from the battlefield, reclaiming, and salvaging it.
We`ll see what other infomation we can come up with in the next few days on your grandfather`s unit so check back often,