The frames were stamped on TF. The frame stamp was the same as the VIN except the prefix was not included. Your stamp is very near a 1959 Vin.
1. As HB has said, there are many ways to determine what era the frame is. Internet pics, shop manual drawings and dimensions. Ebay chassis for sale, lots of ways. Including if the body fits the cab mounting and all of the other features fit. It's not that hard. The 55.2-59 1/2T frames are all the same. Just that there are short bed, long bed and panel/burb slight differences.
2. Clean the frame again and be sure that is a "2" before the 59. If it is just a gouge or stamp tool edge, then you have a 1959 frame. So 59B12331 would be the typical frame number for a 55.2-59 truck. 1959/Baltimore plant/unit number.
The frame can be stamped in more than one place.
3. If your state checks the cab VIN with the frame stamp, you could have problems.
4. Buying the right brake lines is definitely not a big worry. You can plumb them with pre flared straight pieces or bulk line, a tube bender and flare tool.
