OE replacements for M Sport II suspension

[DeVfrodan]

I'm new here, so I apologize if there is a definitive answer on this already - I searched and used a few threads to gather some knowledge, but I'm still lacking a bit.

I have an '03 540i/6 with the M Sport II suspension that I recently bought it through Cars and Bids. One of my front shocks is leaking and needs replacing eventually (not totally blown out yet lol).

Through the few hours of learning I've done, I now know that the MII shocks are the same as the M5 shocks (31312229612). OEM shocks are comically expensive ($500+ here in Canada) and it seems finding the direct Sachs part is literally impossible, at least here in Canada or through any of the parts sites I know of (here and the states). There's the SACHS 556 838 / 556838, but it's apparently a direct replacement for MI shocks, not MII.

Whoever made this spreadsheet is a legend - https://docs.google.com/spreadsheets...it?usp=sharing

Now, in that spreadsheet, the Bilstein B8 Performance Plus 35-114093 is mentioned, and on ECS it is listed as an OEM replacement for M5's. It's mentioned as OEM replacement in a couple other places too, but Bilstein's own description of it says it's for use with lowering springs and describes it in a way that it is an aftermarket performance shock. I am beyond confused.

My question is, is that Bilstein shock OEM ride quality or stiffer?? So far, it's the only viable non-OEM shock I've found, and if it's not OEM softness, then I might just bite the bullet and drop the sucker considering how
expensive the OEM shock is - I'm not trying to spend $500+ on a friggin shock!

Anyways, any and all help and information is appreciated, including coilover suggestions that aren't rock-hard and are soft enough to daily - it's a 5 series after all, comfort is part of the equation.

Thanks,
Devfrodan