...I think it might be a bit strong.
Having cleared beautifully with the sediment all at the bottom, I've take Shirlthegirls advise and racked the wine off into another demijohn.
I measured the SG whilst I was about it, and had a little taste, as you do.
The sum is (1104 - 988)/7.36 = 15.75%.
Tastes quite nice, actually - a bit vanillery/chardonnay - but rather more like a spirit than a wine....