Portlock rhymes with:
flintlock, matlock, tatlock, whitelock, whitlock, ashlock, blacklock, carlock, deadlock, erlach, flintlock, gridlock, hammerlock, havelock, hemlock, kalok, landlock, madlock, matchlock, matlock, niblock, oarlock, overlock, padlock, roadblock, sealock, shedlock, sherlock, shylock, spurlock, subhlok, tatlock, warloeck, wedlock, wheelock, whitelock, whitlock, woodlock
Portlock sounds like:
portales, portals, prattles, prothallus