According to Sheldon Brown
the difference between ISO and JIS is not the angle of the taper, but rather that the cranks are manufactured such that an ISO crank will sit further out on a JIS axle than it would on an ISO axle, and vice versa. So there are several potential issues with using the crank of one type on the axle of another:
A. Altered chainline.
B. Increased or decreased tread/Q factor
C. The taper on an ISO axle may not be long enough for a JIS crank to fit properly, and instead the crank may bottom out on the shoulder of the taper
D. An ISO crank on a JIS axle will not be as well engaged, i.e. a bit less of the crank will be on the axle.
I've just compared the fit of my Cyclotouriste LH crank on the following axles:
1. The original supplied and still used TA axle.
2. A Shimano UN55 cartridge, i.e. JIS taper
3. A Campag cartridge, i.e. IS0 taper
The distances between the inside of the crank (the surface against which a washer goes) and the end of the axle were as follows:
1. TA axle - 4mm
2. UN55 JIS - 5mm
3. Campag ISO - 4mm
It looks to me therefore like the TA Cyclotouriste uses an ISO taper, which is also the taper of that expensive modern TA Axix bottom bracket sold by Spa. There are various other cheaper brands of cartridge bottom brackets available in ISO taper, e.g. Token, Tifosi etc.
Note that this is completely at odds with the information in this 2008 thread
, when a forum member contacted the TA importer and was told TA cranks are JIS. However, TA's website currently states that the Axix bottom bracket is ISO taper, and it seems unlikely that TA would make its current premium BB in ISO taper and its cranks in JIS taper.
I don't know what length axle you would need, but FWIW my TA axle measures 116.5mm and was sold as a double axle. I've never bothered to measure the chainline with that axle installed, and any variations in the symmetry/asymmetry between brands might mean that the same axle length for different brands could give a different chainline.