There are two basic types of spring compressor. The Harbor Freight one pictured below is the kind you want. There used to be one made by K-D tools that was available at NAPA or other "real" parts stores for about $25-30. The other kind looks like a large C clamp, and can only be used if the head is off.

I have never heard of spring compressors being engine-specific. The only thing at all like that I know of is a special spacer that is required for 4 cylinder Alfa Romeo engines, as the springs are down in wells in the head. The spacer is used with the C clamp type compressor.

Some engines other than pushrod Volvos have a separate piece that goes under the valve spring(s). I once had a B20 where someone had put a washer under each spring in an attempt to increase the tension, presumably to allow it to rev higher. This is not a recommended practice.