The two Clansman PRC-349s that came faulty are now up and running.
With antenna to antenna testing on the bench, Ive found that a fully quieting response at a 1m distance requires a -40dBm output from the Marconi 2955, with 3kHz max deviation and 1.5kHz deviation on the 150Hz sub-tone. The radios response to the sub-tone should be sensitive to a tone deviation of around 1kHz or higher.
Both radios needed a bit of work and the protection link LK1 replacing. Ive done a temporary fix there using 0.2mm tinned copper wire taken from a bit of 7/0.2 stranded insulated wire. This has far too high a fuse rating (about 5A) and will be replaced with 0.14mm rated at about 2A when I get it.
The only issue with these two radios now is that they are missing many of the case screws. So as soon as I can replace those screws they will be fully usable.