i converted a pushbike to Electric (using lifepo4 battery) - the battery cost more than the rest of the kit

what i need/require
an EV that will hold 2 adults and 2 children, does at least 60Km on one charge (120Km would be ideal)
1)am i being unrealistic?? with what i want??
2)came across this site while doing my initial research.
http://www.plasmaboyracing.com/whitezombie.php
the reason i was interested in this was because of the engine 'Siamese 9' Dual armature series-wound.
The idea being that i could use a direct drive system (doing away with the gear box) and the computer system changes the configuration for power at high speed driving.
is this a good idea?? or would a gearbox be better??
3)just a rough guess - how much would a conversion cost if i did it myself/got someone else to do it
spending 50K plus on a new EV (like the Volt) is not an option. (and i personally can't see the price hike from the US to Au.
any help appreciated