Sorry for the issue you ran into with your DISA. I should be able to confirm in the next few days if there is a correction that I need to make and I will make it. But the measurements I have are correct for the part that I have been provide.
As for replacing the DISA back into the intake, you should not need to used the screws to seat it, but it will be tight. The new O-ring will be tighter than the original and you should use silicon spray or a light coating of oil on it.
Also note that for many owners even if they replace the DISA O-ring to address the vacuum leak, the DISA make still need to be replaced for other reasons due to shaft wear and issues with vacuum actuator and electrical solenoid that actually control the DISA.
I am going to add info for an additional test to perform while the DISA is out of the car that will hopefully be simple and easy to do.