So, the reason the capacitor was ineffective was not because of stray capacitance, but the cap itself is bad out of the box. I changed it and have around 50dB suppression. REwinding the toroid coil got my sidebands stronger - so it's working but the new cap, which came from the same bag of eBay parts, is not really right. I am going to find a new cap and buy it, sometimes, surplus parts just don't perform in critical applications.

As to a receiver build, I bought a nonworking Heath HR1680 and got it working to specs (it is seen in the first three posts in this thread), and I've got to modify it for AM operation. BUT, this transmitter will only do 30-50 watts when I am done, so I was going to build an amp to 200-400 watts after this is done. But I will admit, last week, I was thinking about building a matching receiver. My 1680 is solid state, it would be appropriate to have a tube-type receiver. So maybe................