I have worked on some Rangers. This article is by far the best done and most comprehensive of anything I have seen: http://www.crompton.com/hamradio/JohnsonRanger/RangerRestoration.html

If you finish that article's refurbishment, you will have a "Ranger Done Right."

There are also popular "mini mods" on the AM window on the net.

There is no point in me attempting to duplicate the fine work that has already been done.

If I were to select a driver for the Johnson desk kilowatt, I would consider the Eico 720 and 730 modulator rather than the Ranger. Yes, they are separates instead of a single box unit, but the Eico is a good sounding radio. It still suffers from the ailments of the rotary function switch similar to the DX60 and Ranger, but is a whole lot easier to work on. The Eico does not cover 160 meters, but that is not needed for driving the desk KW.