Those are a nice looking pair of spurs. Have you examined these with a magnifying glass to look for a makers mark? Sometimes it's hard to find without one. If you were offered $300 by a dealer, rest assured they are worth a minimum of double that. Looks like it's gonna be pretty hard to trace the livestock brand. Here is a start for you, showing a few Triangle F brands from Arizona-
https://books.google.com/books?id=o...EIITAB#v=onepage&q=brand "triangle f"&f=false
Here is a link that mentions the registering of a Triangle F brand in 1887 in Texas under the "CONNELL AND EUBANK RANCHES" here-
Ranches
Personally, I would contact this guy and get his opinion on them and whether they are worth spending the money on to get them restored. Some old spurs are worth thousands. Even if they aren't marked certain people can attribute a maker simple by the construction methods used and the style of the spur itself. This is one such person-
Bill Heisman
Bit and Spur Maker
Current President and Member of the TCAA (Bit and Spur Maker)
b.heisman@att.net
Here is one of his articles-
Spur Identification