Hi Mikey,
I opened up the plug gap from the normal 18 to 36ish & the spark was OK.
The compression when tested was low so have removed the head, ground the valves & obtained a head gasket.
Now; I've had the bike for over 60 years & each time, in the past, when removing the head I've had to give it a belt with mallet to free it.
This time the head, the gasket, & the gasket to block floated free.
I think I may have hydraulic the engine which would account for the non start & compression.
Time will tell.
Will let you know
Cheers,
Wally