Re: #4...#5...?? Which taper?
The Brux couture is very close to Browning A Bolt barrel.
My current build is a Brux #3 on a Remmy long action in a laminated stock cut for a factory Remmy barrel. The #3 Brux would not even start to fill up the Remmy barrel cut stock, if I wanted to make the recoil lug cut where Remmy does, right at the shoulder.
The #4 Douglas profile that I have on my Browning would not fill up the Remmy barrel cut either.
So I had to push the barrel shoulder out 2 inches from the recoil lug to give me enough meat to fill up the barrel cut in the stock.
Southern precision said that if I wanted a Remmy profile, I should order one.
So you could call them if you want your finished rifle to resemble a Factory Remmy.
Otherwise a #3, #4, or #5 can be made to work.