The 470 ohm is there to protect the diode from surge at power up. The filter cap is where to start things. You can add resustance before the rectifier. nut you can just as easily adjust the voltage divider that follows.
I have AB763 in front of me. There is a 10k pot and a 27k resistor to ground. If you want to lower the bias voltage for higher current through the tubes, lower the value of the 27k. You could just as easily raise the value of the pot, but it is so much easier just to tack in a new resistor.
The AA270 has a 1k before the diode, sure, but it also has a 3.3k above the pot and a 15k below it. That is very different from 10k and 25k. But it is the ratios that matter, not the actual value. Looking at the later drawing I also see that the pot is a balance control, not a bias level control. The 763 is a bias level control, not a balance. SO the pot doesn't enter into the bias level on average in the 270. It is simple enough to rewire it for bias level.
So if all you did was change the 1k to 470, I don't doubt it wasn't right. You have to change the whole voltage divider, not just part. If you want to drive the bias voltage lower in the AA270, reduce the 15k bottom resistor or increase the 3.3k upper resistor in the voltage divider.
Or rewire the bias supply like the 763, and don't forget the power tube grid resistors are also different between the two.