Holy shit, eat some more man (TIA being a lady I presume), sorry, just joking, that's probably my two legs added together.
Okay, I have no idea, and have not seen anybody on this forum changing springs on the standard shock. I would suggest you get hold of K-Tech in the UK and ask them the question. I have no idea what the dimensions are in the F3 shock so can't even recommend an Ohlins one.
Maybe send Al at Design Corse an email and see what he can come up with, he's supplied me springs in the past.