Will this modified clutch disc work?

[Mrmerlin]

I am refitting my 2001 R1150GS with new clutch and spline shaft.
As you may know the spline shaft is not fully engaged into the disc hub on this model of BMW,
there are approximately 4 MM of unused splines on the hub.
I have a machinist that is going to modify the clutch disc .
I am using a new Seibenrock clutch disc it has a thicker single piece of sheet steel holding the hub and friction material.

NOTE the Sachs disc is composed of 2 thinner pieces of sheet steel that sandwiched together then the friction material and hub are riveted to these pieces

What he proposes is to depress the disc web 4MM towards the transmission this will entail fitting clamp rings around the disc center and its edge next to the friction surface and then pressing the center area thus deforming it.
This will in effect look like a funnel.
Does anyone have any idea if this idea will work and the disc will not be damaged or fail at a later time.
The machinist says he is very experienced with metal forming and it should work.

It is easier to deform the metal than to remove the factory rivets and machine a new spacer and rerivet the hub to the sheet steel.
Anyone else ever tried this idea?
Will the deformed sheet simply crumble because the force isnt tied exactly to its centerline?
Thanks for your thoughts.

[Mrmerlin]

Here is a picture of the discs the Siebenrock disc is on the right