Can't tell you what it fits but does it say "George Lawrence"? GL used to be a top notch holster maker in the NorthWest US area. Story I heard was that he went bear hunting with a pistol one time and didn't come back. I had several of his shoulder holsters for S&W double action revolvers and M1911 pistols back in the late '60's and early '70's. He also made some nice looking western style fast draw buscadero outfits.
If that is a George L. holster, you might want to check carefully before selling or trading it. The company is out of business and I don't know what effect that may have on surviving holsters made by them. Many of the holsters in earlier years were not as tightly fitted and boned as todays holsters. George's holsters were of this type (non heavily boned) but were well made. The holster looks like it would fit many single action or even double action revolvers. May be a trial and error fit though.
What you have is a very good holster from the George Lawrence Company of Portland, Ore. The company was founded in 1857 and for about 125 years was one of the premier holster makers in the U.S.
The Model 120 Holster which you have was based on the Tom Threepersons holster which Sam Myers of El Paso, Texas had done up at the request of the lawman Tom Threepersons in the 1920s or so. The Threepersons did very well for Myers and was a popular rig and influential. One of the folks it influenced was Elmer Keith who took a variation of it to George Lawrence and had him add a strap with a long tab to it and market them as the Model 120. Below, on the bottom and to the right, is a pic of a Ruger Blackhawk in an M120 by Lawrence. The rig on the right is also an M120. You can see how the guns fit into the rig.
Now the model you have is floral carved and has leather strap trim. It it is lined it's one of their top of the line rigs. The 120 is the style "F" means floral carved, I'm not sure on the Z as my catalog does not show that feature, the T means Trim. The 507 I'm not sure of.
I've added a pic of a Threepersons rig from El Paso Saddelery made for a 1911 for comparason purposes.
Don't have any Lawrence leather for SAA's but if it's anything like El Paso's Threepersons, it won't work for adjustable sighted guns. Just not enough room for the beefier topstrap.
Interesting thread. I understand that Lawrence is out of business now?
Anyway, I have one that has been well cared for, and stored properly.
I know this is an old thread, sorry, but I found it via a google search for more information about this company.
-Bruce