I think that is for a full 12V when cranking and once the starter quits it goes dead.
For the coil you need to find 12V when the key is on and when starter is cranking. Use a test light or volt meter. The original coil wire does this but if its a resistor wire (8 V at coil) you'll need to change it. Trace it back to the bulkhead connector under the brake booster you could remove it from the plug and rewire with a new 12 ga wire. Its a huge pain in the a$$. Another option is to find a source on your fuse box, and run a new wire THROUGH A RUBBER GROMMET to the coil. Never just drill a hole and run a wire as it will rub through and cause a short or a fire. There is some blade plugs on the fuse box you could use.