Not an easy question to answer.  A lot depends on the components used but considering that the electric system weighs a bit more than an IC figuring in motor, muffler and a full tank, you can deduct the weight of the motor mounts and nose reinforcement needed to withstand the IC vibration.  All in all I'd say that the weights overall would be about the same.  It is in my case flying a 660 sq. in. model ( Hunt's Crossfire ) which weighs just over 64 oz.
Alan Resinger

Alan is right, it is not an easy comparison.  What I have learned is you do not build an electric plane the way you build a gas plane.  The electric power system does weight more than a gas power system, but the weight of an electric plane (less the power system) can be much lighter than a gas plane (less the power system).  This is because the electric power system does not subject the air frame to anywhere near the stress that a gas engine does.  When converting a gas plane to electric you need to give thought to what can be thrown out, or made lighter.  Examples of this are the beam mounts, plywood thickness, amount of plywood, use of epoxy, type of covering and amount of dope, type and amount of paint.  In short think about every place you can pull weight out, and don't worry so much about the plane shaking apart.  Electrics don't shake like gas, a lot of what goes into a gas plane is to compensate for the vibration the gas engine make.  Electric planes don't use harsh fuels that undermine the structure of the plane, keep that in mind when building an electric plane.  

Hope that helps.
Andy

Nice ship, beautiful pics...

Marcus