If you are going to change the filtration system, don't do it arbitrarily. Choose a system that has been proven.

You will have noticed that many filters fit the B18/20. As long as the thread is 3/4-16 UNF, and the filter body isn't too tall, it will fit. The gasket-diameter is almost always the same. That doesn't automatically make it the right filter, though.

Why then did Volvo choose one type of filter? Well, it's got to do with the internals. It's the pressure drop across the filter element, it's the pressure needed to open the pressure relief valve and the pressure needed to overcome the anti-drain-valve. There are so many different filters around, but few suitable for this engine.
If you were to choose a filter which needs very little pressure to open the pressure relief valve, then it might open to soon when applied on the Volvo engine leading to too much oil being bypassed the filter-element. Or when too strong a spring is used on the anti-drain-valve it will obstruct oil-flow through the filter.

The Mann catalogue states that the pressure needed to open the pressure-relief-valve is 1.1 bar. The pressure needed to overcome the anti-drain-valve is 1 bar.