Thank you. Are these the changes you are describing?
is whether R3 is necessary, and if so, are the values of R3 and R8 appropriate?
EDIT: With VCC at 7v maximum, I'm not sure that the 74HC07 will turn on the MOSFET. I was thinking that it could be connected to 12v.
I said that 74hc07 has open-collector output, but did not explain what the benefit of that would be. The 74hc07 chip itself would be powered with 5V. Because it's outputs are open-collector, it won't be damaged if those outputs are exposed to 12V
ROW pins pull high when active and high impedance when passive...COM pins pull low when active and is high impedance when passive...
I do not agree with your, here is a schematic from the hc07 datasheet:The diode sort of spoils your explanation.