T420/T430 and their -s variants have an LVDS connector. The only retrofit of a Haswell-gen Thinkpad screen that's gonna work out-of-the-box is to a T431s, which was the first to switch to an eDP connector.
If you have the requisite knowledge (stealing an eDP lane from the docking connector, creating a modded BIOS, making your own custom cable), then you could retrofit one to a SB-gen Thinkpad. Not sure about the other lines, but you'd run into the BIOS flashing issue with the X230.
I also wouldn't just nab any screen willy-nilly and plug it in and pray it works, at least not without looking at the pinouts. Seen too many cases of blown fuses (and thus effectively dead mobo until they're replaced) for me to recommend that. Even then you might have to flash the eeprom on the panel to get the system to recognise it.
I've accepted defeat when it comes to getting better panels for my T420, X220, and X230.