RE: Electrified Lanier Sea Bird
Battery is easy. You'll want a minimum of 100 Watts per pound, so that means about 650 Watts. You could get it out of 14 NiMH cells at 47 Amps, or 16 NiMH at about 42 Amps. That's about a 4S or 5S LiPoly. A 4S LiPoly at 50 Amps, or a 5S LiPoly at 40 Amps.
The hard part is the motor, mostly because of the limited clearance for a propeller between the engine pod and the fuselage. If we knew that, it would be academic. For s&gs, let's assume there's room for a 12" prop because the plane calls for a .60. With electric, you almost always want to fit the largest possible prop.
An AXi 4120/14 on a 5S LiPoly with an 11x8 or 12x8 prop is my first choice, being most familiar with this particular brand of motors. For cells, I'd either use enough of the new TP1900 packs in parallel, like 3, to get up to 50 Amps, or the new Kokam 2000 (15C) or 2100 (20C) cells. For the 15C Kokams, 2 packs in parallel, and for the 20C Kokam 2100s, a single pack is adequate. The only issue with a single pack of Kokam 2100 cells is flight time. The plane will be light, but the flight will be short.