The fire at NPRC St. Louis in July 1973 destroyed approximately 85% of service records of all individuals who served from 1917 to the early 1960's. You can submit a request, but if you have the information to satisfactorily complete the forms (the SF 180 you send initially and the others you'll receive), you already have all the info you need.
Also, your subject could not have been killed in late 1943 or early 1944 unless he was a POW or he was fighting with Filipino Guerrillas. The Invasion of the Philippines didn't occur until October 1944.
His deceased file will contain his service number, unit and other useful information. You can use this to gather information from other sources.