I thought I had checked all the previous caning threads on the site, but your question was almost identical to mine! Your thread didn't conclude with how it worked out for you in the end. Did it look good? It sounds like we have pretty much the same seat dimensions (both seats).
I like the idea of using string, instead of wasting cane (assuming more than one try). All of the how-to guides I have seen show nice even holes, but these are fairly uneven, although the average spacing is consistent. Since I'm just repairing, and not restoring, I want to retain the original frames. And like yours, the original cane was long gone. There are broken off pieces of dowel in some of the holes, I'll be pushing those out. Might be left over from the original caning process.
Your link also shows some examples, that's great. Thanks!!
... the old guys I was referring to was the original builders, wasn't calling anyone here old!