It is made in the 5.2 mold and then shortened by trimming the transom so that total length is 5.0m
Do you think they were able to leave the beams in the same location? Wouldn't chopping the transoms move the rudders forward, thus moving the center of latereal resistance forward under the old sailplan causing weather helm? Did they move the daggers forward? The factory can do these things easily, homebuilders converting a 5.2 would struggle.
So, chop the transoms, move the beams (new tramp?), move the boards, new sail plan (several tries needed), etc...tough way to go. Just buy a used T4.9.