If you add the wire #2 to wire #3, 72" + 191.25" for model #2, you'll get 263.25" overall. This is measured from the bottom of wire #2 to the top of wire #3, and does not include the length for the top hat, so electrically this model is longer than it looks already and is longer than the actual antenna, which I set at 257.375" for 27.205 mhz. So, we're close on the math. Do you own an I-10K?
NB, the measurements I used here are controlled by the element diameters and I just guessed at an average diameter out of convenience, so I could use two wires and no taper.
In order for us to consider specific measurements and their effects, I will have to set the radiator and radial elements to the specs using taper.
There may be another issue that has to be considered as well. The radials in this model are symmetrical, and the radials on the I-10K are not. That could make a difference as well, because the feed point location is set right over one of the radials and this makes the feed point for my model #2 and #3 in error relative to the real antenna. I did this and used straight wires, because it allows for convenience in modeling and tweaking the antenna. Now that I feel good about the trombone matcher working as expected, I need to fix the antenna and try and duplicate to the "T" for the specs. No more convenience in the model, just a lot of work and a lot more to consider with each adjustment.
A model with 22 wires and over 400 segments is not so simple to work on, without loosing your mind or vision...trying to consider everything necessary. Before I start experimenting with the matcher and length, I want to really get it as close to specs as I can.
I know you're anxious to prove your point regarding the .64 over the .625 element, but that will have to wait until the model is more correct.
