I'm surprised to hear of anyone wanting an SME IV! When I had one umpteen years ago, people were dumping them used for about $50 Canadian. The problem with them, as dealers told me, was that SME had backed the wrong horse--light weight cartridges that would track at well below one gram. When heavier and much heavier-tracking moving coils came into ascendancy, the SME IV was horribly unsuited to them. Their "bearing chatter" was said to be horrendous.
I'm just passing this on, since I'm not competent myself to speak authoritatively. Still, I'd check VERY carefully before investing in what I believe to be an arm that missed the boat, if I may change the metaphor from horses.