Adjustables are what you want if you have them. Most cams with Higher lift have a smaller base circle to make lift. Many times measuring for new pushrods is a must.
With adjustables you can accurately set the preload on the lifter without all the hassle. That would be my thought. Yes I know all about adjustable push rods. Saw many fail and the result was not pretty or cheap to fix.
T/A engines had adjustable rockers with hydraulic lifters from the factory . Go figure