No dash lights

Don't know what panel this is. Most instrument panels are made of pot metal or thin stamped sheet metal. Most screws into either material are short, threads in housings easily stripped. If its a rally panel, one of the 3 screws at center pod are the better choice.
If you plan to add a ring terminal and toothed washer at a screw that attaches the circuit board, you might need a slightly longer screw.
When I add a ground wire I put male female spade terminals in the line a few inches from the panel so my added wire will unplug like everything else, ( except the amp gauge of course ). I terminate my ground wire behind left kick panel. this so I can drop the column, take a bunch of stuff apart, retaining my ground for panel testing.
p.s. Yes there are 2 nice machine thread screws into the speedometer but rubber isolators prevent any ground path there.