Summit doesn't 'make' anything,, Surgi gets the low bid from whatever offshore, patent infringing POS that will make a clone of a 'real' part,,, and put two nickles in his pocket. The guy is a shrewd business man, I'll give him that. But my money will go for the USA made part if possible (the $100 you save worth costing someone their job???)
Think about what your usable RPM range will be and select parts accordingly. How often do you expect to be spinning your motor to 6500rpm?????? Yeah that's what I thought!!,, why buy a intake or exhaust that is intended to improve high rpm performance if 4500 is the most you will probably ever see. And cruising at 1500-1800 is more the 'norm' of daily driving.
Your 327 will be a bit lacking in real low RPM , but by the same token you will undoubetedly run a cam that is suited to pushing a heavy truck around on the streets. Don't get carried away,, SMALL cam and SMALL tube headers will serve you well here.
More is not always better.
That 2116 is intended for "idle to 5500" rpm... sounds just right to me!
For headers I'd HIGHGLY suggest something like Headmans 'Torque-Step' headers.
http://www.summitracing.com/parts/HE...%7cYear%7c1970
But that's just my 2¢,,, might be worth 1/2 of that