If there are standoffs on the flywheel, it is meant for 225mm pressure plates. If the flywheel is flat faced, it is meant for 215mm pressure plates.
Likewise, locating dowels are only used on 225mm pressure plates. 215mm only used two shanked bolts to locate it to the flywheel.
Racing Beat (I think) used to make steel flywheels that were flat faced and you used thick spacers in order to use 225 pressure plates on them. This may be where your ".315 spacer" confusion lies.
Looking at your first image, it looks like you're trying to bolt a 215mm pressure plate to a 225mm flywheel. This clearly won't work