Looks to be this one: BladesUSA - Decorative Western Revolver
According to the description it's a "Western Style Navy Revolver with Ornate Engravings", so probably the Navy revolver with modifications as u/colt707 suggested.
Navy is only available in RDO, or with a mod for offline story mode as others have suggested. But honestly looking at Navy and Schofield revolvers online it's almost a like a hybrid, so you may be able to use the Schofield in story mode.
https://www.amazon.com/gp/product/B004UNEFFE/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
The stand it comes with is just cheep plastic, but the gun is at least diecast. I laminated two pieces of what I think was maple (cant remember) then routed the top to create the raised platform and a 45 degree all around.
I reused the two pieces holding the gun but painted them black. Didn't have time (or skill) to intricately carve or turn those out. Added a longer 45 cut to fit the plaque in.
Stain is Early American (https://www.homedepot.com/p/Varathane-1-qt-Early-American-Classic-Wood-Interior-Stain-339710/305502001)