I'll echo what Montclaire posted.
Save the original harness and don't ever toss it. Roll it up into a box. When it comes time to do repairs on the YO harness, I can't tell you how useful it has been to have the original. Both for reference and sometimes for parts. Nothing wrong with the YO/M&H - might be the best we can buy. But over time little faults and flaws will come to surface.

For example, here's the ignition run wires at the ballast terminal. M&H after 15 years, and original '67 without their connectors (plastic coverings).
After replaced the terminal with a Chrysler style/Packard 58, the M&H connector was too loose and didn't hold ther terminal in place. But the original connector fit perfect.
Second photo shows original ignition 2 (Start) terminal with its Chrysler (Packard 58) connector and next to it the M&H (Packard 56) connector,
Little stuff. But the little stuff can be important!