This isn't about theory, it is about a practical engine for a P51 kit. The OP was confused by the kit recommendation of a glow 1.08-1.5. He is looking for a simple glow to gas equivilent. I did not get the idea he was building a pylon racer, did you?

+1 on the DLE 35R, has more then enough power plus some cowl slimness and stock rear pitts like muffler.