The short answer is yes, but please review 14 CFR 61.151 through 61.159 for the requirements. The answer to your question will reveal itself when you do a thorough logbook review and ensure you meet all the requirements in 61.165 (b). Of course you will also need to ensure you have an Instrument Airplane Rating as well as take a FAA practical test for Additional Category and Class Rating added to your exisiting ATP. Check the ATP PTS for more info on the tasks required.