I have a felt f90 which comes with a sora front and tiagra back derailleur and is a triple. I would like to wipe the whole thing and move to 105, but unfortunately money prohibits that right now. OVerall the bike rides great EXCEPT for the sora. Would it be possible to buy an older 8 spd 105 or ultegra front derailleur to replace the front sora? I am not sure if there would be any issues w/ compatibility. Thanks.