Hi raoshashank66.
Practicing with retired GMAT questions, aka "official" questions, is typically a key part of successful GMAT preparation. One good source of official questions is the Official Guide e-book, available on mba.com.
Additionally, you could practice with official questions posted on GMAT Club, such as those tagged GMAT Prep (as opposed to GMAT Prep (Focus)), most of which are from the legacy official practice tests.
To achieve your target score, you should shoot for high accuracy when practicing, even if you need to spend more time per question than is allotted per question by the GMAT.
A good approach to practicing is the streaks method, which is outlined in the following post.
How to Ace the GMAT Using the Streaks Method