Perhaps this may help, it is from a 1979 O'DAY memo...
Rhodes 19 Standing Rigging Specs.
Headstay: 1/8” x 19’6 1/2”
Upper Shroud:1/8” x 19’3 1/2”
Lower Shrouds: 1/8” x 11’7”
Backstay: 3/32” x 28’4”
Jumper Stays: 3/32” x 14’ 9 ½”
All Standing rigging is SS 1x19 type wire and lengths are with turnbuckle (where applicable) closed, from eye to eye (most riggers measure with turnbuckles half-closed, so be sure to note this and/or bring old rigging to rigger to measure for replacement)