The LongRanger started out with a straight C-20 - it needed all the help it could in that airframe.
A more common and useful engine was the C-20R (the Soloy "LR" conversion). It made the LongRanger into a good lightweight utility machine with excellent fuel endurance, but was temp limited and not much use hot/high.
The L1 was heavier, the C28 burned more fuel and was still useless hot/high - not much of an improvement. The L3 used a C30P which still burned lots of fuel and had acceptable hot/high performance, but was once again torque limited (in a hover you don't dare think about left pedal).
The L4 is a good machine: the engine, transmission and drivetrain are well-matched to provided good performance, it has acceptable endurance, good useful load, and a cabin layout well-suited to longline or internal cargo carriage.
If I had to make up a good utility fleet I'd choose LR's for the light jobs and L4's for intermediate use. Good machines, easy to maintain, simple and relatively cheap to operate.
And you don't need to use a "steam engine" to make them fly.