The answer is partly a matter of individual taste and style. This US English speaker thinks that this test sounds better than the present test. There's nothing ambiguous about "this" if you've already indicated the test in some way so that we know which one you're referring to.
The present test sounds strange because present means "right now". But the test probably isn't right now, if you've already gotten your grade for it. The only time I can imagine saying "I scored 70 on the present test" is if you get some kind of instant grade and you're still sitting there. If any time has passed, it isn't present any more.
The phrase you're looking for might be the latest test or the most recent test. Those aren't ambiguous even if you haven't already referred to the test.