well the resale value after a conversion is less. Unless you keep the original parts intact and don't lose them next time you move.
a series E lens from a charity shop is pretty cheap and they are all AI-S, you need to look if you disbelief this. The early all plastic ones look a bit ugly but take the same pics as the later ones with metal rings.
What you need is an early single coated non AI and a series E for their different signature, the early one is digital friendly but that is heracy -