The BPMR6F plug is no shorter than the plug you have now.

I get asked this question a lot and the only way as I know of is to use a 14mm to 10 mm plug adapter and use CM6 plus or 14mm to 1/4 32 adapter and use 1/4 32 spark plugs.

But to do this you have to use a shielded ignition system because the CM6 and 1/4 32 spark plugs are not a register plug.

The draw back to the 1/4 32 plugs is they do not last as long as a BPMR or CM6 spark plug.

Milton