Eventually got around to measuring the cable on my 56A.
Overall length of outer cable 2.11m (83″) 6.12mm od, overall length of inner cable is 2.193m (86 3/8″) 1.5mm diam.
Throttle lever end has a nipple 6.12mm dia 3.28mm thick and carb end has a nipple 5mm long 3.26mm dia (these are as close as I could measure). The adjuster on carb end is 32mm overall with 18mm threaded section. Cable with adjuster for carb end can be threaded through handlebars from throttle lever end, easier if a length of wire is threaded through first.
Hope this helps.