Howdy Bob,
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Your second picture provided a better view... I think I figured it out.
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The "big" 2-pole relay appears to have a micro-switch - or some sort of auxiliary contact -? attached to it (see your pic that I annotated).
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The micro-switch (or aux contact) (I believe) is actuated by the big relay arm. The "big" relay contacts provide the RF switching (input & output), and the micro-switch/aux contacts provide the bias control via the purple and [barely visible] green wires, which bypass the bias resistor (R-27 on the schematic) located elsewhere.
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In any case, it appears everything is right there on top, and it should be easy to modify it with a pair of vacuum relays, and a third high-speed relay for bias control.? You'll have to fabricate a little bracket to mount the relays on, and then replace the OEM "big" relay with your new bracket & relays, in the same location.
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Also, just as an FYI, those Greenstone vacuum relays (from Henry Radio) are pretty compact (see pic below). A pair of them won't take up a whole-lot of room, and should easily fit in the old OEM relay location. I have a pair of them on-hand for a Heathkit HL-2100 project that is on the bench.
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ON EDIT: FOR SOME REASON, MY TWO SMALL PICS ARE NOT COMING THROUGH... Oh well.
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73,
~Alan
Alan - W5ARM
