Hold a second here. I think I’m confused now. Here is my understanding of how the input is wired in respect to the 68K resistor.
The TIP of the input jack goes through the 68K resistor into pin 2 on the 12AX7. The 68K resistor is a grid stopper resistor. In general, this serves to eliminate radio frequencies by working with the tube capacitance to create a filter. So the signal flows from Guitar Plug tip to Input tip through 68K resistor to pin 2.
The shielded wire is not entirely necessary. Grounding the shield on one end serves to better keep outside hum from entering the amp at this wire. The more noise that gets introduced early means more noise gets amplified along the way. A quiet input is important.
I am pretty sure this is the right way to wire this up. I think Deep that you have it right there.