Hi,
I've had a few of the streamlined Hudsons over the years and have replaced the motors on one or two.
Years ago I installed a constant intensity lighting setup, maybe it was Circuitron? These were in pre-DCC days. It still works very well and uses a 1.5 V. grain of rice lamp.
There are probably better options today with LEDs and you can make up your own circuit* but for simplicity you might want to look at some of the offerings from Evan Designs.
https://www.modeltrainsoftware.com/collections/hobby-leds/products/universal-solid-leds-for-transformers
*Or if you want to make your own:
http://www.pollensoftware.com/railroad/index.html
The drawbar has to be connected to supply the left-rail power to the motor. This was a very common arrangement for both brass and plastic steam locomotives back then.
You can use a 9V battery to test the motor direction. You are right that the NMRA standard has the right rail as + would make the locomotive move forward. The headlight wires were probably also soldered at the motor terminals but it has been years since I have looked at mine so I don't recall.
Good Luck, Ed
I would like to know how to repower a 1970's HO AHM-Rivarossi NYC Streamlined Hudson to operate reliable. I operate trains on DC and use Atlas Code 100 Nickel Silver Track. I removed to original motor and replaced it with a similar sized one. I would also like to have a headlight that lights up when the locomotive is running. There are two wires attached to the motor, but they are not currently connected to the locomotive. Does one wire from the motor go to the locomotive and the other one go to the tender. I have tried to operate the locomotive without the tender attached for testing but have had no luck. I feel that the locomotive should run forward when the right rail is positive. I like the looks of streamlined steam locomotives like this NYC one.