Ethan-

For hunting in the Paso Robles area, look first to see if the area you'll be hunting is a 'lead free zone'

Loading for a double rifle is special business. Your goal is to get one load that performs in such a manner that both barrels print groups that run 'in paralell' with each other's trajectory when shot from field hunting positions.
'Lead Sled' and heavily sandbagged bench positions won't get you results that will work for actually using the rifle, also many double rifles and big bore bolt guns have had their stocks ruined in the 'Lead Sled'

Also, you'll find that your rifle wants to run ammunition of a certain type -- you won't likely end up with 'light varmint' and 'plinker' loads that hit together and/or to the sights on your rifle.

Furthermore, it's strongly noted all around the world of those with experience with the double rifle that monolithic solid bullets (like the Barnes X or A-Square solids) are a big No-No. Barnes will tell you otherwise, but trust the years of experience of owners and builders who have either ruined their double rifles or have had to repair and re-barrel double rifles due to the use of mono-solids.
Spend a little time looking around this site for discussions on loading for the 9.3x74r and see what's worked for others.
You'll find a lot of good information here.
There are a couple of specially made mono solids out there that are designed and built to account for this issue, but they're expensive, and they're made in small quantities.
I think that one of these bullet makers has recently gone out of business due to metal prices and supply chain issues.
So, if you're planning a hunt in the belly of the state's coastal region do your homework on what ammunition is legal first, then evaluate your path from there.

Not much like loading for a bolt or single shot rifle!

On your stock repair, I don't have a stockmaker to refer you to down there in Southern California.
Many folks from around the States send their rifles to JJ Perodeau at Champlin Firearms in Oaklahoma.
He is one of the most highly qualified double rifle mechanics in the US and is actually a fully credentialed Gunbuilder from European Guild training and trade.
He can make you anything you need, lock stock and barrel.
His rates are fair and his work consistently comes with the highest praise.

Give him a call and ask about price and turnaround time.

--Tinker