Your car looks really nice!
I understand your concern. My street car with dry sump and full interior (but no roll cage or fire bottle, of course) weighs 1660 lbs with me in it! I don't know what your rules or budget are and I certainly don't think I could find 200 lbs. but I'll just make a few comments:
1. Your driver's seat looks pretty heavy. If it's as heavy as it looks, you might consider a fiberglass seat. I guess you need a passenger seat!?
2. I wonder if you really need or want the boosted brakes.
3. I think I would do without the carpet and upholstered dash, crashpad, and tunnel.
4. In one of your pictures, you appear to still have the window lift motor. Do you need that? I didn't see a window, but if you have them (have a motor and no window?) you could replace the glass with lexan. Quarter and rear windows, too.
5. I would get rid of the emergency/parking brake bits. (can you have rear discs?)
6. Do you need an alternator? How long are your races?
7. The letters that spell LOTUS are MUCH bigger than stock! Just kidding!
I don't know if any of those suggestions are practical for you. Maybe they might give you some ideas...