Drupal 7 Code Review Needed

I am looking for an experienced Drupal 7 Devloper to do a code review on a piece of work that we are having done. The piece of work in question is rewriting a simple cron. The cron syncs data from a MS Dynamics DataBase to Drupal 7 Database through an api. The developer has been asked to rewrite the cron so that instead of grabbing all data on a sync, it only brings across the changes/differences. We are doing tis because the current cron job fails on timeout and we are told it is because of the volume of data. What we need you to do is 1) Make sure that the cron is working as we want 2) Estimate the time it would take a developer with more than 3 years Drupal experience to make these changes. We are not in this instance looking for developers from India or Pakistan to do this work as the work is curren;t being done in India. You must have excellent English and be able to explain this clearly to us. For you to be picked for this work, YOU will also need to be able to demonstrate you have several years of experience in Drupal and working on Drupal 7.