Adam -
I've been riding these cranks for 35 years and never given another thought to whether a spindle is ISO or JIS taper. There may be some very subtle differences between "modern" Campagnolo and Shimano square tapered arms, but I'm fairly sure the TA arms do not care. I have used a Campagnolo NR bottom bracket with 70-SS-120 axle and thick cups and TA crankarms with good results and no distortion of the space time continuum. Doubtless some smart person will point out the error of my ways however.
I prefer Phil bottom brackets which can be adjusted laterally to get the best possible chainline. For a double chainring setup on a "classic" bike with a 126mm rear axle dimension (over locknut), a 115mm spindle length works well. For a triple, a spindle length in the range of 119 -122mm.
As for spindle length, you want to use the shortest spindle you can get away with. In general shoot for the inner chainring to be 3 - 5 mm from the chainstay, and the crankarms equidistant from the stays. The TA cranks (Cyclotouriste) used a slightly longer BB for a given setup than did a campy crank. The table I remember from the Phil BB sizing chart was:
112.5mm = Campagnolo pista 115 mm = Campagnolo double = TA single 118 mm = Campagnolo triple = TA double (campy "Z3" axle, TA axle ref 343) 121 mm = TA Triple (TA ref. 344)
If your bike has a rear overlocknut dimension of 130 or 135mm, you might add another 3 - 5 mm of length, or 1.5 - 3mm of offset to the spindle. The Phil's wide range of available spindle lengths and adjustability will let you adjust things to get the best possible setup, taking into account overall width (Q), chainline, front derailleur capacity, and centering of the crankarms with respect to the center of the bike frame.
Sight thru the freewheel to confirm alignment with the center chainring. Remember everything is a compromise.
Mark Petry
Bainbridge Island, WA