quadracycle conversion opinions please

hi hi
I have purchased a ligier quadracycle with the aim of converting. it is less than 400kg with the existing 505cc diesel unit. it has none of that silly brake servo business to worry about. it currently uses a variator type transmission which seems an integral part of the motor and i believe to be a bit lossy(?) it seems to need about 7 turns on the diff to get a meter of on road movement so thats 7000 for a km? my plan is to use a lynch type 8kw motor, so thats around 3000rpm max. I only want a top speed of around 90kph/55/mph so thats 10k-11k rpm right? so any ideas how to connect the motor up? sorry if this is a bit basic but dont have anyone else to run it past
thanks for your time