If the current stock is inletted and headed up properly and of good quality, perhaps it can be remodeled into a more classic design that fits you.
JR
This would by my first thought, if the wood is done reasonably well, you might be able to salvage whats there removing the white line spacers and but pad and fitting a leather covered or a silvers original pad, and reshaping the stock to and having the checkering cut in a period correct manner, shouldn't cost more than a couple hundred bucks (to American for a Brit to say that ). The gun simply might not be worth spending thousands on and if you can make a vast improvement without breaking the bank your doing well in my view.
Secondly is the but transplant but this is only really worth bothering with if the Inletting, choice of wood, and condition of the head of the stock is well made to begin with.
If you can afford the restock or if money is no object just dive in, you will end up with a gun that looks how it should and handles how it should and fits you if its done well, and it should last several lifetimes.
Edit to add, pictures of the gun in question could help with an assessment of weather the first suggestion is possible.