12 volt wiring--- lets see if I have this right

Helping an older gent get his 1940 9N tractor up and running agian
The wiring looked rough and had been messed with by someone previously so I'm starting from scratch.
There was no key switch and the power to start was being turned on using the light switch but the lights were disconnected.
This is a 12 volt system with a 6 volt coil.
The GM style alternator had the main charging wire going to the starter relay stud where the battery positive attaches, not on the terminal block but I don't see a problem here. There is a wire going from the battery relay stud to the terminal blocks center screw.
The 1 and 2 terminals on the alternator had the connector on them and the #1 terminal was connected to the main alternator wire but the #2 terminal wire wasn't connected anywhere.
If I read the various threads correctly, the alternator will not charge at low rpm using only the main charging wire, therefore I need to use an indicator lamp with a 94 bulb tied into the switched side of the key switch???
Am I putting 12 volts to the indicator lamp via the key switch with the ground side going to the #2 terminal on the alternator?? Kind of confused here???? Is this right??
I also read about using a diode but got lost here and the info I read was vague. Which way is preferred and what diode would I need???
The 12 volts going to the coil only went through the one added resistor which ohmed out to 2 ohms. It did not go through the oem resisitor/terminal block. Is this where you ohm out the coil and add resistors until you get 4-5 amps???
I have purchased an 8NE10306 resistor but they say that it is .6 ohms so I figure that it was intended to be used inline with the existing resistor on the terminal block. Is this correct???
The amp meter was not being used. Both wires were landed on just one of the amp gauges threaded post. In lieu of the amp gauge, I have purchased a lighted volt meter that I will hook up through the key switch if this sounds reasonable. The gauges light will be wired into the new light switch that I bought. I will have to change the lamps out in the headlights because they were never converted or hooked up since the 12 volt conversion---I assume. I will wire the new 12 volt rear light via the light switches line side 12 volt terminal(or maybe to the terminal boards center screw) through an inline fuse and toggle.
OK I've typed enough here for the night.
Lets see what this info generates.
Sorry for being long winded.
Thanks in advance. Jim

Welcome to the forum!
The wiring diagram below should answer most of your questions,
complete with the diode part number.
Compliments of, and thanks to, forum member JMOR.

For the voltmeter, remove the ammeter from this diagram
and connect the wires together. Then connect the voltmeter
as you mentioned, between a keyed power source and ground.
(not where the ammeter is shown)

One thing I noticed is that you said the alternator wire was
connected to the starter relay. Is that really a relay/solenoid
or is it the original mechanical switch under the battery tray?
That switch is activated by mechanical linkage from the thumb
button in front of the shifter. That thumb button is also a neutral
safety device to keep you from starting it in gear.
I recommend hooking it back up and using it if it is not.

yea, relay probably wasn't the right term
here.Mechanical actuator or ^^cutout relay as that
diagram has it.
Using this diagram I see I was incorrect in my 1-2
numbering on the alternator connections. I got them
backwards.
Is the part about the 1 wire alternator not putting
out at low rpm correct?

"Is the part about the 1 wire alternator not putting out at low rpm correct?"

Yes, at least in my experience. My one and only one wire does
not start charging until I rev it up some. I don't have to do that
on any of my three wire conversions. Since you already have a
three wire alternator, I would certainly hook it up that way.