pulley internal diameter

(I'm not sure which section this goes in)
I'm talking to someone to machine out a crank angle sensor wheel (36-1 missing tooth) center. I'll fit it between my round tooth crank gear, and acc. pulley (I can the acc. pulley down the required amount). What I need is someone to tell me the diameter of that part of the crank, it seems that my new, cheap calipers give different readings depending on how it's positioned, so I'm hoping someone here has a better number to give me.

This is on a penta AQ171C

Don't know if AQ171 is the same, but a B230 is 36mm. That's the ID on my round tooth crank gear. Just measured it a couple days ago.
Dave B