Well my first thought is that many mention that after the 'programmer' board is loaded with the arduino as ISP sketch, then there is a need to have it's auto-reset feature defeated by inserting a resistor or a capacitor to the reset pin and either +5vdc or ground respectively. Don't recall the value as I always use a real ICSP programmer, but I think the resistor value was around 150 ohms or if a cap was used instead around 10ufd. You should let ours verify this before jumping in.
A second issue you may have once AVRDUDE can talk to the board running and tries to read the 'target chip' is that you might get a 'signature bytes don't match' error as I'm not sure a 328-PU is the same as a 328p chip and AVRDUDE won't be happy if the signature bytes not match what it's expecting.
Lefty