I don't particularly like the black sleeves shown under the top here, and will probably wear it mostly at a warmer time of year with no long sleeves underneath. Anyway, this gives a better idea of the pattern's "sleeve" length.
Shifting the underarm curve: if you've seen the alteration where you move a bust dart by drawing a box around it and shifting it up/down, this is basically the same idea. Here, the blue line is the old curve, the magenta line is the new one, and I used some horizontal and vertical guidelines to shift the curve up the right amount while keeping it parallel/square to the original pattern. I then extended the underarm to the existing sleeve hem cutting line, and blended up to a much larger size at the hip.
To copy the curve so I could shift it, I used a piece of tracing paper. As long as there are no important marks on the tracing, once the pattern is cut according to the new lines, the tracing can be taken off and discarded.
The altered back, with a much larger size at the hip, raised "armhole" (underarm curve), and smallest size for the neckline/sleeve width
The front was altered in the same way as the back.