I do not feel this is the spring used on this car as it doesn't look like the one seen in an old photo.
Looking for an original throttle spring and I looked through the factory parts book and one of the numbers listed was 2658308 and a friend had one as it was the only spring listed for a 66 with a 273.
Even though this spring was listed in the 67 parts book they do not list applications for each spring. Still need to do some recearch.
The original spring off the Valiant looks to be an original that broke and was shortened.