assume nothing with the MCAT. The diagnostic tests are shorter, low-pressure, and the whole situation is different. You need to be consistently scoring in your minimum target range on ALL sections on FULL-LENGTH, timed practice tests before convincing me that you are going to get your target score. Do not underestimate the test-day freakout factor. Also, you could easily end up getting tested on your weakest content areas in PS and BS, which would drop your score.
A 6-7 is woefully inadequate, and there are students who have to work very hard to get up to a 9-10 on every section. We can't tell if you're going to have an easy time or not. In my experience teaching MCAT, there is nothing "routine" about a 10-point improvement. For most people, it is possible but it takes work.
good luck