If it is actually a rifle (depends on the barrel length... there is also a 760 carbine) and it's NOT a .222, a .223, or a .257 Roberts, the value is
100% - $375
98% - $325
95% - $275
90% - $250
80% - $225
70% - $200
The carbine is worth $450 in 100% condition, and drops to $275 in 70% condition.
If it's a rifle in .222 or .223, it's about $1200 in 100% condition.
A .257 Roberts rifle is $850 in 100% condition.
The odd calibers really only have higher value in 98% or 100% guns, since they are more of a collector's item rather than a shooter; collectors, if they have a choice, only want perfect or near perfect guns.