Ian,
If I can just give you some advice or rather some observations I made, I think you are placing way too much importance in the exact dimensions. In my throttle, I literally took guesses for everything by just looking at pictures from Airliners.net. I did not know about Markus Pilot and I agonized over these dimensions while trying to measure parts of the throttle in the pictures and comparing them to parts with a known size in the same picture.
Strangely enough, I came pretty close & the end result on my throttle is definitely not exact, but it is now more than close enough for me. I don't even think about the dimensions anymore and I really could not care less that they are not exact.
All the handles feel right to me when I use them and in the end, that is what really matters (to me at least). Now, I know that everyone is different and to some, this would be heresy. But I really think Markus Pilot has all the dimensions you really need unless nothing but an exact replica will satisfy you.
That's a decision that only you can make, but I just wanted to point out that many of the things that tear you apart when building will fade away as distant trivial memories once 'the thing' is finished. It did in my case and I can't believe now that I wasted so much time on so many trivial details.
Having said that, if I was to build another assembly of some sort, I'm sure I would still agonize over some details, but maybe not as much now :-)
Maurice