FWIW, not your size but to give you some sort of yardstick to start with. The Zenoah G20 (1.20) is designed to replace .90 sized 4c. So as you scale up to your size glow you can use the same ratio to get what size gasser you will need.
The take off weight on a glow will often be more due to the fuel needed in your size range, but the landing weight will be less cause you have burned off 18oz of fuel where the gaser is using 8-9 oz for the same flight.
This size range its hard to make a choice, larger and gas is it, smaller glow wins. Good luck