Regarding Singer SV models, there is virtually no information available about them. The term SV is also subject to some conjecture, the best guesses are Special Version or Special Variation - no-one knows for sure. They could simply be an experimental variation of the standard model or could be a version specifically ordered by a purchaser, again no-one knows for certain. Manuals for SV models appear to be non-existent (if, in fact, any ever existed).
SV models are likely to remain an ongoing mystery. Yours, by the way, appears to be in very good condition.