It's not a datsun..... still CRAZY but. My parents own a Goggo Dart, and this is MADNESS. They are dangerous enough already!! Might help with the conversion to datsun!!
I have put a weber off a renault 12 onto a couple of datto's they work well on a12/14's. try Aussiefrogs.com for a carbie and get the adaptor from supacheap
you can get twin weber manifolds for a GX head new from JTS in western sydney. I think he may even have a manifold for an a12 on the shelf as well. PM for his number.
You could get a downdraft weber setup fairly easily, that would make a big difference. What exhaust do you have on it? Weber work best with a bigger exhaust setup.