After Market Cluster Gauge Lights

[ACK]

The PO installed a cluster gauge under the dash in my '64 C10. They originally didn't light up, but I tracked down the issue and they're now plugged into the fuse box and lit up. Now they're always on when the truck is running, I would prefer to have them work with the dash lights. I can think of 2 wiring options and would like some input:

1. Splicing them into the brown wire on the headlight switch
2. Splicing them into one of the dash light wires since they're closer and will allow dimming

I'm leaning towards option 2. Is this the best way to go or is there another option?