David Harrington's 1996 Honda Civic is one that is finished and on the road, 96v is giving them a top speed of 65mph, that would be a pedal to the floor top speed, I suspect that it doesn't take much to get up to 45mph, a little longer to get up to 55mph and that 65mph takes a long stretch of highway, so if you need to go 65mph I would go with a higher voltage, less voltage sag and if you don't need the top speed then you don't use it!
144v is common, so there are a lot of components that are designed for that voltage including chargers, controllers, contractors, dc to dc converters and so on.
With those pouch cells, they can not be loose, they need to be under pressure or the chemical reaction inside is not a fast or complete, so they don't perform as promised, if you look at sets of lithium batteries you will see them banded together or threaded rods holding them together, at our local electric auto club they were talking about putting lithium batteries in a press or vise to get the banding around them and not finding a max pressure rating but more so the max pressure is how strong your end plates on your banding is.
Transmission, most people put it in 2nd or 3rd gear and "forget about it" but being able to shift gears is nice for highway speeds and for climbing hills, you might for example find that 2nd gear in town works and 4th gear in the freeway works well.