Inductor waveform not increasing when supply is increased
The diode (D1) is the problem - think about what is happening - you draw some current through the inductor then use the mosfet to "release the spring" - what should then happen is that the LC tuned circuit resonates and this would naturally produce a "recoil" voltage that rises up to twice the supply rail and down to nearly ground. The action of the capacitor restricts the peak voltage to 60V and pushes ALL that energy magnetically towards the load.

Having the diode there just returns most of that energy to heat in the diode. Try a simulation without the diode.

Think about it another way - the long term average voltage across an inductor must be zero (any scenario period) - this MUST mean the waveform rises above and below the Vcc rail. The IRF630 can handle 200V so this won't be a problem unless you mis-drive the MOSFET and take so much energy into the coil that the capacitor cannot adequately take away all that energy before hitting 200V. If you think this might happen use a 30V zener in series with the diode you currently have installed.