You would do better if you could identify his Platoon or Company. Best would be Squad. In the Army a Battalion has anywhere from 300 to 1,000 soldiers. A Battalion is made up of 4 to 6 Companies and Company is made up of 3 to 5 Platoons, made up of 2 to 4 Squads. http://usmilitary.about.com/od/army/l/blchancommand.htmhttp://usmilitary.about.com/od/army/l/blchancommand.htm
Do an internet search of online books for his name + WWII. May run across a memoir written by someone of your dad's unit. Try www.archive.org too for "427th Armored Field Artillery"
Also do a search dropping the word Battalion.
Someone on ebay is or was selling the photos of a Veteran of the 427th when was in Philippines.
I also believe WWII News Reels are online. Do you know where he enlisted or lived while in the service? Allot of local newspapers had pictures of the "local boys" in uniform. My husband's basic training graduation picture was used, along 3 other men representing 4 branches of service, in his hometown newspaper advertisement asking for support of the local Red Cross war effort.
Contact his siblings if still alive or his cousins. Usually at least one child of the parents received the trunks or boxes of parents stuff, Family Bible etc. that may have undiscovered family treasures, especially if any still live in the parents "home town".