Hi Energy vs Pro Magnum HFT lifters

There are 2 lifters Crane currently offers - one is the high rpm type, one is a variable duration type. What camshaft do you have? Do you have the part number of what you have? The "Hi Energy" line of cams should have the anti-pump up already so changing to Comps really isn't a change other than brand name.
I would first make sure that the spring pressures, pushrods, and overall valvetrain geometry are good before you replace them. Valve float is caused by a variety of things from lack of spring pressure to harmonics to lifter bore clearance.