I hate to think about it this early but this year is a big year for me and with my birthday coming up I've thought of looking for something Vintage, I'm hoping to find a 1989 Grand Seiko, if I could find my birthday month it would be all the more sweeter ...
While I am hardly an expert, your timing is fortuitous, as GS got reintroduced in 1989. The 95GS or 8NGS may be your best bet - albeit all GS watches from that time were quartz, with modern mechanical ones only reintroduced in 1998. Hope this helps!