Does the red wire from the engine harness go
to the same spot as the batt wire on the starter?
To scared to power it up and fry my new harness....stress

was to make a wiring diagram, used a multimeter to confirm which wire went where, checked and re-checked, used a perished harness from another B21A to confirm and see how to improve it, then pulled the wiring harness, made a new one that was an exact copy of the old one, with improvements for strain relief and soldered/crimped connections, and heat shrink tubing to seal the ends of fresh black plastic sleeves. Any wires that would be in close proximity to the Engine (heat), I wrapped in Al Foil, before inserting into Plastic Sleeves. But, that's just me, a careful, methodical, perfectionist. Some might say anal or pedantic.

Yes the red harness and battery cable go to the same post on the starter. If you put the blue yellow wire on the wrong spade of the starter then the car will not crank when you turn the key don't worry just put it on the other one. Hope this helps