The 2.0 Zetec ones are FAR too short for the ST170 setup.

I was mislead on this too and i only found out when i went to put my ARP flywheel bolts in, fortunately i realised that 4mm of thread engagement was too little before i went any further and put a new set of ST170 flywheel bolts in.

You *might* get away with it if you use loctite threadlock with the new ST170 bolts, sadly i can't make any promises as i've never tried!