The Ship Who Sang

From back cover of Del Rey paperback 1979:

HELVA HAD BEEN BORN HUMAN

... but only her brain had been saved -- saved to be schooled, programmed and implanted in the sleek, titanium body of an intergalactic scout ship. But first she had to choose a human partner -- male or female -- to share her exhilarating escapades in space!

Her life was to be rich and rewarding -- resplendent with daring adventures and endless excitement, beyond the wildest dreams of mere mortals.

Gifted with the voice of an angel and being virtually indestructible, Helva XH-834 anticipated a sublime immortality.

Then one day she fell in love!