I think the front derailleur is likely to be a problem.
Shimano road and mountain front derailleur have different cable pull requirements. The Sora STI with 3 fixed shift positions is going to be hard, if not impossible, to set up. Switching to a road bike front derailleur isn't a very attractive option either because all road derailleurs are down pull and your bike frame is configured for an up pull front derailleur.
Your canty brakes and rear shifting should be fine.
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