From memory, I recall being really disappointed in the lack of performance gains with shorties, I believe they flow pretty much like cast iron manifolds, I could be wrong. For that reason alone I decided to make the long tubes work whatever that meant. In summary, I had no choice but to use a Borgeson box and it needed clearancing (I was not interested in pulling everything out and dropping the K frame, install engine and headers to K then reinstall K frame to see if that worked) . To minimize dimpling tubes I also had luck with a 1/4" thick driver side motor mount shim. Good Luck!