We're talking about Ceros right?

I'd be inclined to get it running first and then see what weight needs to be saved when its complete. In all honesty I doubt anyone would mind you running over weight in whiteboard matches (unless you're talking 20Kg or something) while you're giving it a shake down run.

I'd finish it off and have some fun with it, you'll get a better idea of what it can do and how it handles before you start to re-engineer it.