inductor value is going to be critical especially if zvs is still on the table.
Interesting construction hints from that site, looking at the 80uh 300a jobbie. maybe 16 turns, and 10 strands (insulated), no twist, and with the size of the hole remaining I'm guessing it was done by hand. Any guess on the gauge? or the toroid size? Wire looks a little thick for 20khz to me. I would think you would want at least 1/2 twist (full twist I mean) over the length of the wire bundle to even out the lengths.
