I really think they would have tried to avoid two Midwesterners on the Ticket, though. My guess there would have been an effort to get Harry Byrd as VP for balance, being a Southern Conservative segregationist
Wallace was not going to run alongside a man who based his career off of being pro-segregationist. Truman was chosen because he was just sympathetic enough to Civil Rights for Wallace to be happy while being vocally Anti-Communist and Southern enough (being from a Confederate State) that the Southern Democrats thought they could keep Wallace in check. Needless to say, it isn't a match made in heaven.