Kryptos K4 does not use a Pollux or Morbit cipher. Neither does the Morse code sheets. At least not Pollux or Morbit by themselves.
I was in too much of a hurry. This usually isn’t a problem but I ignored a very simplistic factor in these two ciphering systems.
The output is numbers. Therefore the ciphertext must be in numbers to decrypt it. This is why I wasn’t able to get a solution.
Yeah, you could use some other cipher that could use those numbers to get letters. By themselves, these two are not enough, they would have to be paired with a number-to-letter substitution scheme. It’s not impossible that this was used in K4 but this falls into the realm of a multiple step problem with all of the strengths and weaknesses those methods entail.
I’m glad to have this cleared up. Fractionated Morse ciphering is still a viable option but allows for the use of a keyed-alphabet so more than a basic analysis would be needed – or knowledge of the keyword.