Sadly you cannot fit ES type forks to a TS frame. Tried it years ago. First problem is the major difference in the headstock bearings. Even if you solve this problem the TS frame is not long enough and the ES forks will clout the engine. You would need to lengthen the TS frame by circa 4″. Don’t ask me how I know!
I do have a set of leading link forks built originally by Mark Dicker for sidecar use with a TS250. Never tried them in anger but they look the dogs whatsits.
PeterF