Chevyman, I am in process of installing a new wiring harness in my own 1963 Chevy pickup w/ same deluxe guage & tach package as you have, but I ordered an original reproduction harness made for trucks that came with deluxe guages, where your kit is more intended for the hot rodder who will later install Dolphin or other aftermarket guages. Your harness doesn't have the simple plug & play connectors that a factory harness would have so if it were me, I'd get that harness you bought put on a Chevy forum and sell it, and re-order a correct original reproduction harness from Classic Parts of America
www.classicparts.com and then every stock thing about your truck will work as it is designed to. They also make correct original harnesses that are only slightly altered from original so they work with HEI ignition.
The tach is on a separate harness, and as was the case with GMC trucks too, your 1963 Chevy would require an external Sun transmitter box - EB9A for V8 and EB7A for 6 cyl. The transmitter boxes used a AA looking internal battery that is no longer made, so you can use a AA and it will work but its best to send your transmitter box and tach to one of the companies who does solid state conversions - they remove the EB transmitter board and install their own which uses modern technology to send RPM information to the tach - they calibrate the tach perfectly with the new electronics and viola! you get a perfect working tach back. They also restore the guage face when desired.
Let me know if you need specifc info to do any of the above but I believe you will be happier if you ditch that aftermarket wiring harness and replace with a correct original design harness.