From what i see and for my part, you have found a good WW1 WESTFIELD COLUMBIA 1918.
The typical frame of the brand, handelbars, chainring and the rear fender does not decieve.
They are superb!
Here are 2 tools ouch original of my collection to give you an idéa, they are made of boiled cardboard to save the leather.
But beware it does not fit on all frames because ther are more reduced locations.
Your stand is mounted on a bike 28", just heat it to red at 2"1/2 of the bottom with a blowtorch to give it the right curve in 26".
It can also be mounted on a COMPAX but with a frame and 28" wheels.
Originally, the G519 are mounted with "U.S. ROYAL MASTER CENTIPEDE GRIP" (photos courtesy @izee2 )
The "U.S. ROYAL CHAIN" are superb but not me who am French it is not possible: buy, shipping and customs multiplied by X bikes...
So, i opted for tires that looked like "GOODYEAR...
I am interested in your G519 project, that's fine.
But in wiew of your frame, i must go on the restoration of HUFFMAN 1942, is the tightening of your seat tube that looks like.
Look at @johan willaert post "1942 G519 HUFFMAN BIKE PROJECT" , it's an original!
That of @tango021 , is made...