Well done
. Try the Zuiko 28mm f/2.8 for starters - reasonable price and a fine performer. I've had two 35mm f/2.8s neither of which was too sharp, I don't know if that's true across the board or whether I just got duff ones. The 21/3.5 and 24/2.8 are both superb but perhaps a little wider that you're looking for at present.
Interesting. I'm on my second 35mm f2.8 and both were beyond excellent and remain my single-most favorite Zuiko for all-around performance. But in reality, there are few duds. One thing about the 35mm focal-length Zuikos is that 35mm is about impossible to focus on the 2-series focus screens. For some reason the microprism mesh that is used in stead of the "ground glass" diffusion surface reacts strangely with 35mm focal length and the 35mm f2.0 lens is particularily difficult. Therefore, focus errors may contribute to apparent sharpness.
However, as the camera in question is an OM-1, the 2-series screen is not normally found nor used in it as it will throw the meter off.
I have the 24/2.8, 35/2.8, 35/shift, 50/3.5, 100/2.8, 200/4, 300/4.5 and 35-80/2.8 Zuikos. Not a dog in the bunch. But I had other lenses which I sold off without sadness.