Answering my own question . . . with thanks to Rod Schaffter on the Atlas N forum. This might be of use to some.
Tie lengths from some flex track:
Atlas Code 80 (USA made): 0.626"
Atlas Code 55 : 0.640"
ME Code 55 : 0.688"
ME Code 55 Bridge Track : 0.747"
Tie Width
Atlas Code 80 (USA made): 0.066"
Atlas Code 55 : 0.055"
ME Code 55 : 0.060"
ME Code 55 Bridge Track : 0.054"
Ties per inch
Atlas Code 80 (USA made): 6
Atlas Code 55 : 8
ME Code 55 : 7+
ME Code 55 Bridge Track : 12