Dhall57: I sold my 76K in the late 70's and no photos have survived over the years.
It was a great ride that carried me faithfully to Calif., Canada, Pa, New Orleans and o Daytona and Myrtle Beach more times than I care to count. My riding buddy had a 74K Boss Maroon Metallic like yours and it too was a screamer with an 836 kit.
As you may know or guessed, I occasionally buy and resell some old school bikes including my favorite, the sohc 750. Back about 5 years ago, I sold this bike to a fella named Mike in
Willmington, NC who may be or was on this site.

It was very much like my old 76 with a stock engine and it was hard to let it go. Looks very much like my old 76K and kinda like yours too.
Here is my current project, a K0 that I am saving from the life of a chopper. Just snapped this one for you after sitting the tank and side covers in place. The HM300's go on tomorrow. And yes, its in my dining which is heated and my garage is not. It's starting to take shape and should be completed in a couple weeks. A good way to wile away the cold winter days tinkering on my favorite bike.

I will keep my eyes open for your stock pipe you are looking for. I see some occasionally.