I suggest you search e-bay and the web for pictures of an original 03A4 bolt.
They have their own look.
I considered conventional bolt forging,found a smith...but,imo,too much heat goes to the cocking cam.I was afraid it would soften.
I turned a steel plug about 2 1/2 in long that would slip fit inside the stripped bolt body.
leave about 1 inch length of a larger shank,so it will stop
On the shank end,turn to about 5/16 to serve as a nipple to slip a tube over.
Then I drilled a 5/32 hole in the end of that nipple,about 2/3 the length of this plug.
Now,with this slipped inside the bolt,see where the root of the bolt handle is relative to the plug,and mark the plug.Cross drill a port to connect to the hole up the center of the plug.
So,what you have is a support,so the bolt body will not distort,you have a small heat sink,but you also have is the means to feed cooling water to the inside of the bolt right at the root of the bolt handle.
It looked to me that they did not notch the rail to clear the bolt handle.
What I did,at the outer edge of the rail,for location,I cut,with an abrasive cutoff wheel from above,about 2/3 to 3/4 the way through the root of the bolt handle,even with the outer edge of the receiver.On the bottom of the root of the bolt handle,you have left about 1/8 in of steel.Later,this will get quickly heated red with an oxy-acetylene torch,and will act as a hinge for a nice downward bend.But,not yet.
First,set up the bolt body in a vise ,with some sort of wrench or cheater,to grab the bolt handle with.Also setup something like a hanging IV drip bottle(open top,for refill) or other cool water supply,and a hose to that plug you made.And,think about the water that will get all over,ahead of time.
That cut,and thin web,will somewhat act as a heat choke,and with a water feed,the bolt will stay cool.
Now,look careful at the pix of an original,and look at how the lower part of the bolt handle needs to be reshaped before you make the bend to turn the bolt handle down.You pretty much need to take the original bend out,and then curve it out some more.You'll make it look like a straight Mauser,them go more,curving it up.Use heat,get it red,bend slow.Let it cool down.
Now,you might reposition it in the vise.You will use water again.Use the torch to heat that thin web of steel on the lower side of the root of the bolt handle.Get it red,slowly bend the bolt down,about 75 or 80 degrees,to what looks right.Let it cool.
So now you have a roughly shaped bolt handle with a wide open vee on the top to weld up.
We used a Lincoln flux core wire feed.My welder friend preferred to not stand in a puddle and have water running while welding.
OK.We had a bucket of water.He'd weld 3 or 4 seconds,then we'd quench,wire wheel off the slag,weld again,etc till it was filled.
This worked really well.The B+S(Browne and Sharpe) stamp on the top of the bolt handle is intact.No heat discoloration at the cocking cam.It all stayed cool.
Now you can tweak your bends to just right,and grind the welded area to shape.
There is still the relief grind to make for the scope ocular.
I cheated.
I measured the scope height above bore,set the bolt up vertical in a Bridgeport with a vee-block,clocked to the "bolt open" position.I put the mill spindle where the axis of the scope would be,and used a boring head and carbide boring bar to make the relief cut for .060 clearance around the ocular.
Consider ,in your bending,how to keep this cutting minimized.It gets a little thin.
With a little more massaging,mine came out to look exactly like the pix of an original.
You may not have all the resources I had,but this may give you something to work with.
BTW,very early,potentially brittle bolts,had the handle turned straight down.Later,strong bolts were slightly swept back.