You're lucky in that the 6L6 is an inherently great sounding tube, so anything you use will sound very good. I've run some CBS metal clads in my Dennis Had Inspire monoblocks and they sound fab:
Be careful though - there's a difference between 6L6G and 6L6GC tubes. The "GC" version is rated for higher voltage, so if your amp is set for "GC" 6L6 tubes, there's a danger than a regular "G" 6L6 might go cherry.
But the reverse is not true. If you have an amp that's designed for 6L6G tubes, you can run 6L6GC tubes in there usually without issue.