I've driven 30L1 from Elecraft K3.
Some simple rules.
DO NOT OVER DRIVE IT !! (repeat that)
Don't depend on ALC feedback. Keep drive levels down.
The Amp has a keying circuit/relay that wants (likely) voltage that your modern box cannot supply. Put together a relay circuit between the keying output from your rig and the Amp.
The other thing I noticed was that the idling current of the 30L1 grids was too high. I put a stack of diodes inline with the keying line to drop that voltage a bit. This brought the current back down.
You may want to beef up the tubes. I put in 572B's.
tom