Union mortice latch for rebated door

[BigClick]

I have a pair of oak doors both rebated. and the latch set is a Union rebated mortice latch.

I know its going to be tricky especially with leaving a thin wall on the catch plate side but I am stumped as to how I drill the 25mm (approx) hole for the latch seeing as the centre line is bang on the transition of the rebate.

Can anyone explain how to go about this?

The latch model is J2650-SE-3.0

 

[EddieM]

Would the below suit?

Might have misunderstood of course.

 

[BigClick]

That’s the one. I have it but I can’t work out how to drill the door for the tube.

 

[BigClick]

It’s done now.
I clamped a scrap price of oak to the rebate to make it flush for drilling then discarded the scrap piece.