Thanks disston, I do have a loaner cover plate that has been machined, it is on my tranny at the moment.
Trouble is, I'm measuring different depths on the input shaft bearing, meaning the cover isn't machined parallel?
The cover thickness has been measured at a given point at each bearing hole, and the precise positioning for the depth gauge is marked.
It may be as simple as taking my measurements from the 3 marked positions on the cover plate.
I'm just concerned with obtaining the precise measurements required.
I'm waiting to speak to the chap who kindly loaned me all the tools to fix my tranny.
Lord of the Bings, kangaroo farmer