The St170 clutch came in two sizes, 230mm and because it wasn’t up to the job they upt it to 240mm half way through its life.
It has a very odd sized center drive so neither will work with your gearbox. Or any other Ford gearbox.
The St170 flywheel is a piece of crap as well.
To mate an st170 to an ib5 You are going to want a flywheel from a 1.8 Zetec. Black or Silver top there all the same. The 1.6 Zetec E is also the same but not the Zetec Se. This is a 220mm flywheel. Clutch could be from several donors from the Rs turbo to mk5 Escort and some Mondeo’s.
There is more than one bell housing pattern for the Ib5. The St170 is not going to mate up to yours. The St150 is a Duratec. The St170 is badged as a Duratec but is actual a tuned Zetec E.
The ib5 that a Zetec will bolt to came from things like the Ka/ Escort/ Mondeo and could be a cable or hydraulic clutch depending on.