Yea, I googled the 116's and they have a 1.75 dia. head pipe. These are circle track headers and I'm afraid you are going to kill off your lowend when you stick them on a stock 350. 1 1/2 or MAX 1 5/8 tube diameter is what you need.
Sell these things and get the correct sized header for your 350.
And 2 1/4 inch pipes are big enough for your set up.