I also have an Electra Cruiser build going, with a Grubee G2A 48cc Skyhawk. Here are some pics for reference.
My plan for the front mount is to get the small universal front mount
from sickbikeparts.com and use aluminum spacers/standoffs in the space between the engine and front mount. Once I have the sizes of everything I will post them here. I think I'll need around 1.5" to 1.75" of spacers, depending on how I adjust the height of the mount on the seat tube.