If we're talking about a 2m plane designed for something like the 140 RX, other than the fact that it was a RE engine, there are a number of other 2 strokes (glow and gas!) that would be decent subsitutues. I don't see a need to wedge a 4 stroke 1.8 when everyone else is using 1.6 or 1.7 4 strokes in their 2m planes - granted, there's probably little difference in size between a 1.7 and a 1.8 but if the model was designed for an enclosed 2 stroke, that's what I would do.

I guess I'll head to find some info on the LDIII.

David.