If no here can help, your best bet is e-Bay. Turn signals, mainly the rear stay (mount), will be the most difficult and expensive part to find. However, they do show up on e-Bay from time to time. A complete set of front and rear will set you back somewhere in the range of $150-$250 depending upon condition. Luckily, you can use the painted version which seem to be more plentiful than the chrome one.
Mirrors: The left mirror is still available new from Honda but the right is NLA. I have seen the right one show up from time to time but it's kinda pricey. If you're ok with aftermarket, dratv has a nice set for about $20. Just be sure they are for a 10mm mount.
http://dratv.com/drbr10stmise.html
Headlight: The HL bucket shows up frequently on e-Bay, but currently the only I see is this NOS.
https://www.ebay.com/itm/Honda-NOS-...012344&hash=item2ce44b2609:g:8ygAAOSw~2VcUMGE
Headlight: The 76 used a sealed beam, which is still available new for about $40. Personally, I modified a defective sealed beam version to use a replaceable $5 bulb.
Carb: Look for a decent carb (minimal corrosion) with the markings "533A" on the flange. Here's one that is reasonably priced.
https://www.ebay.com/itm/1972-74-Ho...289249?hash=item4438a7ade1:g:OV0AAOSwfCZcgV5R