I don't know if this is a good idea...
Electronics do NOT like:
1) Heat
2) Vibration
Putting the coil on the spark plug just increased both.
The only way to combat this physics is just reduce the mass...
This is why Coil-On-Plug designs (for OEM) use a pretty small coil.
So, you're just reduced your coil performance just to get rid of the spark plug wire???
I'd rather run a honking, big coil and run traditional spark plug wires...
Unless you're
RICE RACING with a LOT of money!
-Ted