Let's see .
We know Tungsten coil is ~10x smaller R when cold, resulting in 10x inrush current.
P=V^2/R so R = 120^2/75 = 192 Ohm when hot and 19~20 when cold.
The impedance ratio of core is related to turns ratio, N^2 and voltage ratio = N
If N was 10, the impedance ratio would be 100 more on the output, or 100 smaller on the input.
thus Rin = 20/100 = 0.2 Ohm !!
You got 180V with no load and the source is a center tap 12Vdc bipolar drive source.
You may also be getting some high impedance from the LC filter resonance but without transformer parameters, f and L values, I can only guess the 75W light bulb is the wrong type of load.