What manual diagram are you looking at? Is it the 67 service manual black and brown cover with the 3 needle nose pliers on the cover? If so look at page 12-3 and 12-5 on the right side of the diagram. Are you sure Red isn't really Pink? and that your red and black isn't really pink and brown.
If so your red / black is battery, red / green is temperature, and red / blue is oil. brown / black is brake.
"Will I be able to plug and unplug the bulbs from the back of the dash once it is in? How about the speedo cable? " ....yes but you will be upside down with your head on the floor, your knees hanging over the top of the seat, your feet in the back, and your butt where the small of your back should be. ask me how I know