You folks from the US are most likely much more familiar with the limitations of a S&S or Harley type V2 so no need to give you advise on this type of motors.

My practical experience is limited to some 15.000 miles on a 3Wheeler.
Maybe the best improvement is to eliminate the reduction plates in the exhaust pipes. That gets the engine free breathing, adds torque and horses and brings the temperature down.

Wish you many happy and troublefree miles!

Hannes
once: Green M3W; 2013
now: Red 4/4 Sport; 2011
and some practical cars for use in real life