I'm going to read your approach after you get the results, and we can go from there.
A preliminary analysis of M3 shows that it is much more cyclic than the 340. There are a few missing symbols in some of the higher scoring cycles, but only a few. Not sure why. Top half is comparable to bottom half.
The scattergraph of count versus total score shows basically the same thing. Most of the dots are bunched up really close together in the respective count columns, showing the strong cycling. Symbols 5 and 13 are on the far right because of their high count and they cycle together. But there are a few missing symbols in that cycle too. Symbols 1, 3 and 7 have count 13, but they do not cycle together well, even though I thought that they did at first. I had to check manually to see what was going on. Their scores are high and similar, I am guessing, because they have such high count. With 13 count, there are going to be some short to medium false cycles with some of the other 50+ symbols just because of probabilities.
I am a little bit burned out tonight, so I lazily marked the latest cycle hillclimber with colored boxes showing symbol groups that need further investigation as possible cycles. Because of the strong cycling overall, I am guessing that maybe at least half of them are grouped together correctly, if not more. There are 91 bigram repeats on my list. I haven't tried to solve it yet.
