Lee,
I'm a graph paper and pencil guy myself, but have converted a few track plans between the gauges. In general, when converting an island type plan from HO to O, the main problem is providing access. Invariably, dimensions need to be more than doubled and interior track positions adjusted to provide for access hatches.
I've always liked that plan. At one time I considered using it as the basis for an On30 layout. I think the idea of a long "branch line" ending in a upper switching yard/wye is a good one.
If part of the wye could be run into another space off to the right, you could probably push the run-around track and wye up toward the top of the plan to open up the middle for better access to this trackage. 
Jim
