[jrblasde]

Actually, let's safe-guard that experiment a bit further. Suppose someone used that setup and the gasket paper were inadequate. The transformer and ammeter would be toast!

Okay, new plan. Insert a 1 MΩ, 1 W resistor in the series circuit. Should the gasket paper fail, this resistor will safely absorb the current of a transformer with a 640V high side. Most Philco models have B voltages less than 640V, but I know that my 46-480 has 640V. If your transformer produces a lower voltage, then this 1W resistor will still be adequate.

We might also think about testing DC current, as that's what the gasket paper would be exposed to in an IF transformer. Go ahead and rectify and then filter that transformer voltage, and then use it to test your gasket paper.

The circuit would now look something like this:

Your test power supply:
    Transformer high side -> rectifier -> ripple current smoothing RC network (the output of which we will call the DC power supply)

The test circuit:
    DC power supply -> ammeter -> 1M, 1W resistor -> gasket paper -. return to DC power supply