You don't have 'adjustable lifters' LOL, you likely have adjustable rockers. (Only other "adjustable" possibility is pushrods) What are they off of? In other words are they 273 OEM, or 340 TA, or some aftermarket? If they are OEM 273, of course they will fit, that's what they came under---those covers. If you have aftermarket, they might, or might not