Louisiana.
In #300's life she only worked for one common carrier, the Tremont & Gulf as #28. This is why that road name has been selected. If she had been sold to the Texas South-eastern instead of Southern Pine Lumber Co. (SPLCO owned the TSE) it would have been a no brainer to letter her TSE as the TSE operated the Texas State RR in the 1960's.
At any rate, the only difference between T&G Ry #28 and SPLCo #28 are the intials on the cab. So for giggles we can reletter the cab and run log trains for some railfan event. Who knows, maybe a geared engine might be a guest too.