If Dan used 35 turns for 12V then 70 for 24 is ok.
65 turns delta would be the same as 65/1.73 = 38 turns so that checks out ok.
Ignore your single coil into a bridge rectifier, that tells you nothing.
Using your 70 turns giving 3.3v ac at 120 rpm.
Volts per phase will be 3.3 x 3 = 9.9, Line volts will be 9.9 x 1.7 = 16.9
DC volts will be 16.9 x 1.4 = 23.5
So that checks out for 120 rpm cut in. The only thing I would question is why choose such a low cut in for a 10ft prop.
Yes you could mess about with the blade length but that seems silly, as soon as you shorten the blades you reduce the available power, it would be a last resort if the alternator was too fast.
With your 70 turns you are going to err on the slow side so you can raise the cut in speed by increasing the air gap. Unless you are trying to hold things down with a very long line with high losses I would think that you should increase the air gap to bring cut in up to nearer 150 rpm for a 10 ft prop. If you stall then, add line resistance.
I think I would tend to agree with your 60 turns, but it probably won't let you go up a wire size.
It's nice to err on the slow side, you can always try the lower cut in, but unless you are in a very poor wind are I think you will reduce the total energy capture with the 120 rpm cut in. Partly depends on how much you value an amp for a few hours a day compared with reduce energy production in the 5 to 10A region on better days.
Flux