68 barracuda wiring reverse lights and tach

I'm working on a customer's 68 Barracuda. I bought all new M&H harnesses for the vehicle. I don't have any wires that plug into the Bulkhead from the dash harness to go to the backup light switch to the transmission. I installed the harness with two purple wires into the bulkhead connector that goes to the transmission, but my bulkhead is empty in those two spots.
Also I bought the tach wiring from M&H, and I have two gray wires. 1 plugs into the firewall has a grommet and goes from the coil to tach. I'm curious where the power wire comes from going to the tach under thd dash. I was hoping that wire came with it too but it did not. Also where is the hole supposed to be drilled in the firewall for this tach wire grommet?

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