Looking at your requirements a dimension would be nice but a g2 using bells in scb mode would be equally doable. It has 12 zones on board, and can have a rf portal added on for wireless.
If you have already ordered a flex a bit unfair on the wholesaler to send it back? Any reason for 2 bells? No one takes any notice of one so 2 seems to add complexity for no benefit?
Mk8 keypad is a mk7 pcb in a new housing