How would restoration affect value?
Depends on the restoration and watch.
All the blogs and watch websites go on about unpolished cases and untouched dials.
With very rare or collectable watches it makes sense. With less rare watches my guess would be there would be as many if not more buyers for an old watch that looks new/vgc. I'd love to see some real price analysis of this.
Personally I'd go very light touch: service, clean, replace the crystal and strap. Keep all the original parts just in case at some point in the future randomly turns out to be super rare for some reason.