OM-1s are good but cannot compare with Nikon, Nikons are better.
Zuiko 50mm f/1.4 is very good lens if you find one with SN > 1.1million. I do have one with < 1.1million, which I rarely use.
Zuiko 85mm f/2.0 is very good lens, not particularly sharp wide open.
Zuiko 28mm: I can say it is very good for travel esp., city scapes. I have one with f/3.5 and I shoot mostly @f/8.0 or @f/11.0.
OM + Zuiko is very compact.