That sounds great! It may take me a little research ( and some knowledgeable advice ) to figure out if this will work, though. I haven't found info on a 17CQP4 as of yet, but I've found specs on the 17QP4 which I suspect is closely related.
http://www.shinjo.info/frank/sheets/093/1/17QP4.pdf
Here's the good news! Physical specs are nearly identical! I believe the faceplate is the same shape and size, the neck is the same length, same overall length. Everywhere I see where it would matter, it should definitely fit my chassis and yoke. Electrically, the specs are almost identical to the 17LP4.
But, there are a couple of notable differences. There is one pin that the 17LP4 uses that is missing on this 17QP4, pin 6 (G4). It also states that this tube has magnetic focus instead of electrostatic focus. I honestly don't even know what that means, so I have no clue as to how interchangeable these two types are or what changes would need to be made to make one work in the other.
Does anyone have some specs on the 17CQP4 for comparison? I can't assume the 17QP4 is the same, and I don't know what the "C" in there indicates.