Just so I am clear, are you saying that the following four sentences are all correct and basically have the same meaning, except that number 3 and 4 were used more frequently in the past? I also wonder whether "should" refers to "certainty" or "advisability" here.
1. It was surprising that he committed the crime.
2. It was surprising that he had committed the crime.
3. It was surprising that he should have committed the crime.
4. It was surprising that he should commit the crime.