It's worth qiute a bit more than the Rem 700's. The 40XBR is a benchrest rifle custom built by Remington. I would venture to guess around $1K depending on it's condition.
The 6mmX47 is a 222Rem Magnum necked up to a 6mm.You have yourself one heck of a rifle.
If it were mine I'd be buying a set of 6X47 Redding dies, a few hundred rounds of 222Rem. Mag brass, 66-70gr match bulletsand take it to the range for some tack drivin fun.