Progress is happening, albeit slowly.
Tonight, I measured some RTW garments I have that are similar to this top and used that information to figure out what sizes to cut the pattern from. What measurements? Front shoulder width, back shoulder width, armhole depth, and circumference at bust. A little tedious but having them is a helpful tool.
Like I thought, Size 10 for the neck/shoulders. I'm going to try Size 14 from bust to hem, knowing that I'll be making an FBA (that's full bust adjustment for the uninitiated) that'll add some width to the front of the garment. And of course, those side seams will incorporate some "fit insurance." Easier to remove excess than to not have it.
Next up: tracing the garment front so I can make the FBA without destroying the original pattern. I usually use "The Perfect Fit" by Singer as my primary reference for bust adjustments. From the bookcase, I also pulled "Fast Fit" by Sandra Betzina and Palmer/Pletsch's "Fit for Real People" as back up resources.