[morzh]

You are overcomplicating stuff. You don't need to know field coil ESR as it is irrelevant to anything so much so Philco never shows it anywhere, showing only DC resistance, nor do you really need lytics' ESR. As long as you use proper lytics (most could be any type except the one right after the rectifier - high ripple rating is preferred there).

If your hum appears stronger in certain places of the dial, this is likely an outside interference source(s).
Could even be a power transmission line nearby.

Again, a good way to tell is using another radio.

As for the chassis, you could try to ground detector output (or top of the volume regulator), see if hum persists.