Without making any changes for electric, you will end up about 1/2 lb or so heavier than the glow powered version of it. A Saito .56 weighs about 15.5 oz, a E-Flite power 46 will come in at 10 oz. The mounting system for the electric motor is probably a little lighter, but we will assume it to be a wash. Since you no longer need a fuel tank nor throttle servo, you probably save another 4 oz; however, you have to add an ESC so in the end, you probably save just 2 oz. At this point, the electric system is about 6-7 oz lighter. Depending on size, the battery will weigh somewhere between 13-16 oz (4S, 3200 mah) so you end up about 8 oz heavier. Depending on the size of the model and assuming that it is biplane I suspect that it will not affect your wing loading by very much.

Now, without making changes to the structure, you could probably save a little weight by using mini servos if already using standard servos (ie Hitec 225 or similar: 50 oz-in torque). That could save another 4oz, but for a plane such as this, probably not worth it.

Finally, the radio system could be powered from the main battery through a built in BEC on the ESC or a separate BEC. That will save you another 2 oz or so.

Even though the plane will be a little heavier, the ability to spin a large prop will keep performance about the same, but it could also make it slightly better. This is completely doable.

Teo

PS. I am starting to think that we are going to have to pry the glow driver and starter off someone's cold hands...