Here is a video I shot this morning before leaving for work. https://youtu.be/mW2AFYTe3Rs
Tom,
The EV drivers did not look that bad, other than the easily replaced dust cap. How did you determine they "desperately need to be reconed?"
They are not the original drivers, which were 4 ohm, the EV DL18-MT are 8 ohm, so copying the EV TS parameters won't get you any closer to the original- not that there aren't far better options than either available for a FLH (front loaded horn) of this type.
The split horn path does not appear to be near 7 feet, more like 5 feet, so will cut off (Fc) around 60 Hz (one quarter wavelength), don't expect much output below that. Best to HP around 55 Hz to keep from tearing up the driver cones.
As far as the cheap cones you listed, for the most part, you get what you pay for regarding displacement- most of those have very small Xmax (linear displacement). Cheapo drivers may have only 5mm Xmax, while suitable drivers with Xmax in the 15mm+ range are available.
Doubling Xmax (and power) can allow a speaker to produce 6 dB more output, when you are lugging around a big, heavy cabinet, might as well go for something with lots of output.
Since you mention DIY, you could achieve output almost an octave deeper using a tapped horn design of a similar or smaller size, your FLHs are not going to go low regardless of the driver, putting much money in them won't change that.
Art