I believe you.
And that's way closer to 5?'s measurement than I thought it would be!
Also, remember how I mentioned my friend who tried to make a franken Speedmaster, based on a standard rep case? I found his sales listing from last year. Let me cut and paste:
"Solve your Speedy sub-dial spacing issues!!!! All you need is a gen dial, hands, movement ring, and a Tissot 861 and you have a great Speedy and a fraction of the cost. Gen case back, crown, crystal and dust cover. The rehaut has been machined by JMB so that a gen dial will fit.
Note...A gen bezel will not fit on this case!!!! You'll have to use the existing one or go to a rep plastic bezel."
Now, I don't know what he used for a crystal, but I do remember it being a dome. I also don't think anyone ever bought this unfinished project.