I’ve thought about this a lot. The 13” Mid-2012 Model is my favorite MacBook Pro. It’s built like a tank, works like a horse and near completely fault-proof. Except the bottom RAM slot problem. Taking a look on panelook.com and trying to narrow down for a better LCD by any parameter, the closest I could find to match the size, aspect ratio, signal type etc was this BOE HYDIS HV133WX1-100 (BOE0A28) panel. I don’t see a specific indication for it being IPS, but it filtered down as being IPS in the search engine. Significant hardware difference being that instead of the 30pin LVDS connector, you have a 40pin one. Further implications to me are unknown as I have no understanding in that, but could be something a more knowledgable person could delve into. Would be cool to at least have nice colours and a better viewing angle on our favorite compact form factor, most repairable MacBooks of recent time.
The connection of the right speaker is quite tight and tricky. In my experience it can sometimes disconnect when reseating the logic board. All in all, the acoustic performance of this speaker system is lacklustre. It's a fact. I use Bongiovi DPS system wide audio post-processing software to slightly enhance that poor performance. It works well. https://bongiovidps.com There are other alternatives in this space, but I found this working best for me. Hope this helps.