Flywheel machining specifications

[1880cc]

I've taken my flywheel (Lancia Beta 1756) into the machine shop for resurfacing and they don't have the listing of dimensions in their book. They don't know whether to machine the surface that the pressure plate bolts on to at the same depth as the surface that the disc rubs on. I don't know what to tell them. I'd appreciate it if someone would let me know. thanks,
Bob

[Guy Croft]

0.5mm step between friction face and clutch mounting region!

GC