Idea for a TRUE Slant Six Challenge class

We did this once, only we used a super six. Cut the head .100, ported with a dremel, and found a factory exhaust manifold that had like a 2 1/8 opening. 8 3/4 with 3.55's and a stock 904 H/S (high stall from factory). It was in a '72 Duster.
Sorry to say, never made it to the track, but I'd have guessed it 15's for sure. Short block had like 160,*** miles on it and we never took it apart. It was very cheap, like 150 bucks into it.
Pretty neat to be able at will to burn the tires at will with a /6 auto