Sorry I don't live in Pittsburg, so can't do the leg work for you but....Have you tried.....
1. Pittsburg Gazette (newspaper), 112 Quitman, Pittsburg, TX 75686, 903-856-6629 (someone there might volunteer to lookup the obit for you.)
2. Pittsburg-Camp Co. Library, 613 Quitman, Pittsburg, TX 75686, 903-856-3302