Tim, is that a whole beef tenderloin? Your 70cm thick is impossible.
Could it be 70mm thick?
If so cook at 55ᴼC for 4 hours, that's enough.
It needs a very hot and quick sear to finish for optimum flavour and appearance.
Before vacuum packaging fold the thin end back and tie in place so your filet is about the same thickness throughout and it then cooks evenly.
Roasts that long are more manageable when cut in two equal pieces.
When you invest that much in a piece of meat you might find it useful to also invest in gaining more knowledge about SV cooking. However, relying on internet based information can be risky as the American Presidential elections are approaching.