Command Upgradeable PRR K4 - Which RailSounds Board (e.g. Generic 4 vs 5.0) ?

So I purchased a used PRR K4 command upgradeable set (6-31902) and would like to update it to TMCC etc. I've read that the RS5 boards work. My question is this - which board should I purchase?

I was thinking the:

Unless it was weird putting a Mikado in a K4 (2-8-2 vs 4-6-2 - I'm not knowledgeable regarding that) and should stick to the Generic 4.0 Steam sounds. I didn't see any other RS5.0 board that seemed appropriate. Unless the crew talk doesn't use things like the line and engine #?

There is also a RS 4.0 K-4 #3755 and a RS 4E / SOUTHERN 4-6-2 #1396 that might be a good fit

Thanks!