My penny's worth of an estimate - never specifically measured it, but I'd say 'in the 200s' minimum, maybe 300 even? Depends on the size of crankshaft sprocket, kickstart gearing, compression ratio, force of prod etc. And your Weetabix intake natch. Some bikes have rather low-geared kickstarts, but an A feels 'about right' to me and so I'll guess at 250+ with a decent swing from a practised person of ample proportions lauching the assault after one cylinder is just over compression.
Has to be something like that to start the thing, as a mag won't provide a decent regular spark below roughly 100-120 armature rpm (more if it's manual advance and set part-retarded), which = 200rpm+ on the crank. Many need a fair bit more than that. (Hence that sturdy breed seen pushing things out of pub car parks . . .)