No, matching a driver to the others involves matching a lot more parameters than just the impedance and power handling characteristics. At best, you would need to get a second, matching driver so you wouldn't be mixing drivers in the same airspace -- and that's presuming the cab is subdivided into smaller chambers of two drivers each like an SVT 810, which I don't know to be the case.
Is there really no one who can do recones in the "Golden Triangle"? Are there any decent-sized music stores still left there? (I was thinking they could tell you where they get theirs done.) Even you had to ship it off, a recone would probably better than trying to buy multiple new drivers. Don't you ever cruise over to Houston for funsies? (Sorry...I guess funsies aren't happening as much as they once did.

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