Here are good quality ones that may or may not be lightweight: Phil Wood, IRD Defiant/QB-95, SKF and White Industries. Those are all high quality square taper BBs and I will take better bearings and longer life then weight anytime.

If you want to save weight, remove the Tuggnuts, grab a carbon fork from say Wound Up Composites because they still make a 1" threaded carbon fork. Or you can do a conversion and get a 1" threadless headset from say Cane Creek or Chris King or Phil Wood and then do a Ritchey Comp fork (I think IRD or Soma or Tange basically one of the companies related to Merry Sales Co. also makes a 1" threadless carbon fork). This will allow you to use a lighter weight threadless stem (you might need to shim it if you are using a 1 1/8 stem) then maybe look at a shallower section wheel, a lighter seatpost and maybe a lighter bar either carbon or titanium.

If you wanted to keep the current set up then I would find a lighter weight quill stem and seatpost and swap out bars and of course shallower section wheels.

However me I would probably keep the set up as is and ride the damn bike. It is a good looking set up. I would change wheels and tires for myself to like a H+Son TB14 or similar rim and a tan wall tire and maybe some polished hubs (Phil Wood would look the best but Paul are just fine by me)