Hi Svinao,
You state you are looking for a 40-45mm lens which i cannot recommend as i have not tried any. I can suggest things only based on my experience.
As others said already, the OM3 does not have aperture priority - the OM4 or the OM2 have. I have both of them and they are both fine. I like my OM2n a tiny bit more but the OM4 sees a lot of use too. Personaly, i think the OM4 is more handsome.
I have the Zuiko 35 f/2 but i am not a big fun of it. A bit large for zuiko and nothing exciting. It is a good lens but almost any other Zuiko i used is better. Here is a pic taken with the OM4 and the 35f/2
Personaly, the silvernose 50 f/1.4 is a fantastic lens for b&w, i use it with a lens hood as it tends to flare.
I think it is my favourite 50mm lens - it is not the sharpest (all my nikkon lenses are sharper i think) but i like how it rends the image. Here is a pic taken with the OM4 with the 50 f/1.4 at f2.
You said budget is not an issue but you don't have to pay a lot of money to get a vary reliable camera/good lens combination. This F90x and the 35 f/2 have cost me £170 in total.
Also for less than £100 you can get somethinkg like this. A Pentax ME with the Pentax-M 35 f/2.8 which is a tiny package for SLR.
Once you sort out the jumping exposure problem (any CLA will do that, it is just durt under the ASA dial) it will give you loads of years of good service. Obviously if you can find an LX, that will be even better. Here is a picture taken with the ME and the 35 f/2.8
Good luck with your quest.