I have a Vanguard actioned .300 Weatherby with a synthetic stock. Despite its wispy short barrel it is quite accurate which is a pleasant surprise. The stock though could be better.
1) Is this a long or magnum length action?
2) What off the shelf stocks fit this ?

It is a long action. They just mill the mag box longer to fit the Weatherby cartridge.

Any take off Vanguard or Howa long action stock will fit. Bell and Carlson is good economical choice for this one. Boyds will work as well if you want laminate or solid wood. If you go Boyds, glass bed it. They tend to be a little sloppy in the inletting.

Here is a page of choices from Stockys: https://www.stockysstocks.com/...-sporter-barrel.html

Jeremy