OK, T1 can be the SCR and the coil......my mistake, and I was thinking you mean the ocsilator transistor to change into a FET (thats possible todo).
To use a FET for the SCR will cost you a fortune AND you have to make a signal to close the FET after the ignitionpuls.
A SCR will close by him self after the *ignition* becourse the *backflash* of the ignitioncoil create a negative puls.