Nicely done Kirk!
I'll add to what NJ and a few others mentioned. I just did something similar on a longboard that had damage to the blank that was right at the outline finish shape. I cut it out and put in a new piece of foam with very little glue. However, that "little" bit of glue expanded onto the bottom of the board leaving a noticeable line. After spackling, it still showed, so I sprayed the board white. Problem solved.