The problem is definitely not the plugs. As far as starting goes, any plug will work just fine. You may notice performance issues bit it will definitely start.

I would start at the beginning.

Is the distributor in the right position? see mgaguru.com/mgtech/ignition/ig103.htm

Are the plug leads orientated correctly 1,3,4,2 anticlockwise mgaguru.com/mgtech/ignition/ig114.htm

Also, don't rely on new=serviceable. Particularly condensers and rotor heads.

Hope this helps

I have a 1954 ZA Magnette and have been updating the ignition system. New coil, new points gapped correctly, condenser, leads all cleaned, good distributor cap. I have put in NGK B6ES spark plugs as is the Champion NA8 comparison plug but no luck in the engine firing! I am going to put in Champion NA8 plugs or N5C which is a champion comparison plug and then cross my fingers as I turn the ignition. I'd appreciate any thoughts on the type of plugs members have used in their Magnette engines.
Additionally, I have checked and re-checked and then checked again leads, ground wiring, gaps and power outputs.
Just mainly would like info on the champion plugs question. Cheers.