The bike look really good! I have a 76 K6 too. But started the work away from stock look 1980... it was fun then.
Now going back to stock look except for modified engine, 4-1, mikuni carbs with pods. Tank + side covers with fresh paint and all decals, badges cost a lot...
Remove the bags, and front "window". Bags are Shoei, right? I had a black set used around Europe during the 80's.
Keep it close to stock when your bike look really good. Find another cheaper F1-F2 if you want to make a cafe racer, surgery modifications with no return.
4-1 will not harm the bike when you can switch back to OEM pipes when you want. The seat can also be replaced with the old modification, Giuliari seat.
http://www.wats-motor.com/wp-content/uploads/2011/09/selle-giuliari-honda-CB750-four-4.jpgI regret that I did not buy that seat +30 years ago when it was found almost everywhere for not that much money.
I use Kawasaki Z1-900 mirrors that look cooler and work better. Cheap copies possible to find today, original long or short stems.
Next is another bar, clubman look like old cafe style. I will use that next time. I used drag bar for the last years that was very comfortable. I have a new one just for sure if I do not like the clubman.
That's it, the bike will look good like that.
You need to change the main jets with 4-1, if you want KN style carb pods, main jets one step further.
My carbs had stock 105, 115 with 4-1, 120-125 with pods.
The CB750 look sooo good with these mods possible to change back to pure OEM. It's horrible to see the TV shows where they rape bikes with power tools and saw making all look the same... as a bad Norton Manx copy.
CB750 K0-K6 have its own charm and soul that look very nice and a must to keep. This is the bike that initiated the Triumph's, Norton's way to the graveyard when people made their choice.