Thank you Marker!
Yes, I ought to consider the loco on e-bay, but I bought the one I have an will stick with it: I still don't like it but I am committed to working on it until I do.
And thank you so much for the picture!!!! Note both the roundness of the cab roof and its height above the very rear of the boiler (the looks to be a bit more than a scale foot of drop from cab roof to boiler at the front of the cab) - it is as I described earlier, so this photo confirms what I had determined and discussed with my picftgures earlier, although it tells me I should raise my projected new cab height just a bit more than I planned.
Thank you!