Two shafts more efficient than one...?

Each 90 degree gearset is going to cost you 2-5 % of maximum rpm hp. 1 engine direct drive is - should be most eff. ? Eff. in terms of what parameter and under what conditions ?

Logic tells us that the 370 gas is least eff.-- 480 of Diesel may be more eff.---No doubt the 440 will beat both. That is the purpose of the test. Me, the skeptic, could rig a set of picked engines, to arrive at what I am trying to sell for a living.