I can't offer much help. Here is my info:
http://i111.photobucket.com/albums/n160/jhl99/2011/2011Forum/McKeever-1.png Some of the tracks indicate that I've had difficulty locating trails in the past.... the USGS 7.5 maps and ADK GIS info don't always match up.
That connector definitely looks interesting.
Woodhull Lake to the turn to the east at N43.569, W75.050 (About where Mill Brook is crossed) is not a problem. I've ridden through to Gull Lake and Woodgate a couple times (actually in the reverse direction).
As you indicate the stretch over to North Lake could be a wildcard. The good news is that it looks like it doesn't cross through many boggy areas.... but who knows about blow down. Blown down is a killer in the ADK because of the sandy soil. I doubt remote snowmobile trails get cleared until late in the fall. Maybe the NY DEC can provide some trail conditions?
If I was doing the 33 mile stretch from Woodhull to Nobleboro, I would allow 8 hours for that section... Although you could bail at North Lake Road (Atwell).
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Uncas Road from Raquette Lake to Eagle Bay is nice dirt road cruise.
It's been a few years since I've been up there, but Route 28 is an ok ride until merges with Route 12 at Alder Creek Station (I'm sure you know that). From Alder Station to Utica would not be pleasant, but there seems to be many choices in secondary roads.
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300 miles in 2 day seems pretty hardcore to me. If that ends up being the plan, I would really consider dumping any questionable snowmobile trails.