I cross referenced the info on the HAMB and found a post on that confirmed it. This is the ideal set-up. Low in profile, fold-down lever on the passenger side, and a perfect width.
In addition, I met an upholsterer, Stitch in Time, who works with Mercury Charlie and is interested in helping me create a seat similar but not the exact same as the bench in Mercury Charlie's original Tall T, now owned by John Tullis of Dripping Springs, TX.
A quick Google image search revealed the exact seat to be third-generation Dodge Caravan seat, available from 1996-2000.
I'm posting it here for my own reference and will be on the hunt for one. A good day of sleuthing was had by your truly.