Start with an NGK heat range #7. gap about 30. thats safe for a weak ignition.
get a wideband, learn to read it. it will tell you everything. fuelwise
you can only read a NEW plug 1 time under WOT then kill engine and coast off road and pull 1 plug, what you are looking for is timing and heat range. The #7 's will probably be fine. the timing is read off the ground electrode, Google it and learn.
the old school carb style plug reading will tell you little on injected engines. and even then strict discipline is a must. Good luck and be safe on the road.