The 12AD7 is basically a low microphonics 12AX7 so that will be fine. The 6AR5 looks like a regular audio output pentode so it should be fine for the output stage. You may need to adjust some resistor values to get it biased right.
Edit: 12AD7 seems to be quite rare. Only one pair for sale on eBay that I could find and the price was over £70 per tube.
Cheers
Ian
Edit: 12AD7 seems to be quite rare. Only one pair for sale on eBay that I could find and the price was over £70 per tube.
Cheers
Ian