You should be able to do it for 550kg
My 710Kg included a chassis that was at least 60Kg heavier than necessary
and a "Competition Certified" roll-cage - 30Kg?
Changing the motor to a 9 inch and just being a bit careful should get down there,
Probably won't have to change the gearing - with mine I am 55% on the rear and its pretty good
I think 700amps will let me spin the rear tires on tarmac
I used Subaru parts - yours are probably a bit lighter