I really love what you are doing, this model is prob the nicest looking 120y datsun and rarest for their model.

I have to say great job on the whole thing. The only thing I would suggest is raising the bonnet rear so the radiator air escapes onto the windscreen instead of the belly pan which is smooth and wonderful. The hot air over the top will create a minute downforce effect of warm air escaping up and over the car, its small I know but it all adds up. The other thing to do to your exhaust is cover it completely with heat tape. The thermal insulation will create better gas flow which is a proven method for exhaust efficiency and expulsion.
Maybe the side indicators or reflectors can be replaced with stick on thin ones and the indicator modded (get an old one and file down its height or use tapered bolts the outside and glue the nuts on to the back of the indicator housing flanges. Finish off with flat amber cut-out section from a toyota or other junkyard indicator sections. All minimal gains (except exhaust which is a worthwhile expense and saves on heat building up) but all adds to better results.

You might also look into what the eco-honda did with the wheel arch covers where they just hang like curtains and the turning tires at the front just move them out as out needed.

Overall a great project and a great addition to our website.