[Closed] short dropper post for g/f's FSR

Trying to find a dropper post for my gf's specialized FSR, its a 2007 so doesn't have a full length seat tube. She has 150mm of post sticking out of the frame not including the rail clamping area at the top of the post. However total length of the post is only 315mm.
Does anyone know of a post that is only that long?
Failing that any one know of one I could trim? I think its theoretically possible with my gravity dropper if I cut the spring shorter as well but a big job, I didnt know if any others had "spare" post at the bottom that could be cut off.
thanks in advance!