The interval is 70K, at least it is for my '97 V90, and it is my understanding that you have the same engine. If you don't want to push it it, a 50K interval would not be excessive.

Admittedly, Volvo went through several modifications to improve the interval. The original '92 started out with a 20K interval, but with modifications performed at Volvo's expense, the belt life was changed to 30K. Susequent model years had their own changes from OEM, as I recall, including a wider belt. In 95, when there was several engineering changes,the belt life was extended to 70K, or was it 50K then 70...too confusing!.

Clearly the greatest risk to its failure is a mileage band around that interval. That is, as you approach 70K, the risk increases, I suppose, althought Volvo certainly has a margin of safety in setting the interval. Once you move beyond that, you are just flirting with disaster. Aside from premature belt failure due to a manufacturing defect, it would seem prudent to decrease the 70K to whatever interval with which you are comfortable.
--
John Shatzer, 97 V90 @ 90K; 92 965 @ 106e