The VA is usually a complete waste of time but you may want to contact them anyway. Write to the following address. Include his full given name, date of birth (8 May 1922) and Social Security Number (226-14-6122). Request a copy of his entire file. BE SURE TO INFORM THAT HE IS DECEASED AND THAT HE WAS YOUR FATHER. They'll confirm this from his file.
Department of Veterans Affairs Freedom of Information Officer 810 Vermont Avenue, Northwest Washington, D. C. 20420-0002
What you receive may seem like a lot at first but it'll be mostly medical records; very little other info that you don't already have (and very little chance it will include the info you're seeking).
IMPORTANT: They usually withhold any info that may shock or embarass surviving family but sometimes they fail to examine the file thoughroughly prior to copying and sending it.
(P. S. Forget the toll-free number. It's always busy and, if you should reach someone, they'll simply inform you that all such requests must be submitted in writing anyway.)