Regardless of the pickups you install, one thing you can do if you don't like your treble to drop off when you turn down the volume on a Les Paul is to modify your guitar for so-called* "1950's style" wiring.
All that is required is to re-solder one wire, so it is not exactly rocket science and you can change it back if you don't like it. Look it up.
* vintage guitar geeks like myself will be quick to point out that the term "1950's wiring" is a misnomer. Lots of 1950's Les Pauls left the factory with "modern" wiring the same as Les Pauls have today. Some even had "1950's wiring" on one pickup and "modern" on the other. It seems to depend on who was manning the soldering station that day.
Gibson has always had QC quirks, even in Elder Days.