That's a concern Spud as the flywheel bolts for CVH are M10 fine thread and the Zetec ones are M11 fine thread! As for the flywheel weight the 1.8 zetec and CVH flywheels are only a couple of pounds different and I wouldn't want to lighten a cast flywheel anyway.....
Black top Deffo M11 threads for the flywheel hope you used the right ones
