The reality is that you will likely have to rebuild the finals for power tweaks to best match quieter output tubes. Bear in mind FCC regs.
For quieter tubes, switch the conventionals, such as a 6AQ5 to a 6005, etc.
You may happen across a Johnson Messenger page, I just do not have any substantive references at hand.
: Does anyone have any information concerning modifications to this tube type CB radio from the 60's. Looking for power and modulation tweaks, tube swaps, etc. Thanks