Power from Taillight is wired to fuel sending unit... Check!
The way I see it
74 column on left, 65 harness on right
WHITE -------------STOP SWITCH----------WHITE
DARK GREEN---RIGHT REAR-------------BROWN
YELLOW/ BLACK-LEFT REAR--------------DARK GREEN
RED--------------------------------------TS FLASHER-RED
DARK BLUE--------------------------OUTPUT OF 4X flasher
LIGHT GREEN------------------------RIGHT FRONT--TAN
YELLOW---------------------------------LEFT FRONT---LIGHT GREEN
DARK GREEN------------------------HORN BUTTON--BLACK TRACER
I don't know if you 65? had? a 4x flasher. IF not, wire a fuse from a constant hot, through a flasher, and hook to that DARK BLUE. If you already have a hazard flasher, it should work OK if it is already wired, but you will not use the switch on the column.
You can check the colors to the switch with a continuity tester light
Make a truth chart to show what connects to what
With switch "in center" stop slight switch should hook to both rear lamps. Fronts should not hook to anything
With switch to left, flasher should hook to left front and left rear, and brake switch should still hook to right rear
Opposite for right turn
With column hazard turned on, blue should hook to all four lamps front and rear