If those are chokes, where did the 220ohm measurement come from? if measured from the "chokes" they must be wire wound power resistors, because you can't find a choke like that with that high of resistance. The fuse is your power coming into the circuit, the chassis is ground, and those transistors don't have the collectors connected to the heat sinks internally, so heat sink pads not issue (metal mounting screws would be an issue too, so nylon screws would be used because non-conductive). lastly, what you think is the cell output, looks like the primary center tap to me(either normal center tap or bucking coil center tap), and that rec bridge you think is connected to alternator is really the cell output. In his schematics he shows another switch on the HV positive side, but most likely the primary switching accomplishes the same kind of signal on the secondary, from the primary "switching noise" which normally would be smoothed out with a capacitor on the output : (Kept It Simple, Stan) .
push pull converter
Transformerless Push-Pull
Class AB power amplifier. (P.S. We don't need to worry about "cross over" distortion with DC pulses!))

http://s12.postimg.org/5u6ucorf1/20150826_143648_1.jpg
Also note: If his memo's mention "amp restriction" than the primary most definitely bucking coil arrangement. But easy enough to test once you have it set up on your bench.
push pull converter
Transformerless Push-Pull
Class AB power amplifier. (P.S. We don't need to worry about "cross over" distortion with DC pulses!))

http://s12.postimg.org/5u6uco
Also note: If his memo's mention "amp restriction" than the primary most definitely bucking coil arrangement. But easy enough to test once you have it set up on your bench.