In my opinion, the one record Belichick should aim for is getting his overall winning percentages over .700. That is very feasible even if he doesn't want to coach for too many more years.
Assuming Bill wants both records, if he were to coach for 7 years and finish with 12-4 records (no playoff appearances) he would be tied with Shula for wins and have a .694 winning percentage for first. If his record were 12-5 (assuming a playoff loss) he would still be tied with Shula but now be in second with a .684 winning percentage. Based on how the Patriots have played under Bill, I think he could easily obtain both records if he were to coach 7 more years in New England. Realistically, he should have both records as his own within 6 years. All of these assumptions are based on the current regular season of 16 games and playoff setups with 2 wild cards.