3 on the tree conversion

I just recently had the same issue. I have a 68 Barracuda with a slant 6 and 3 speed manual xmission which had 3 on the tree but I was missing the linkage so I decided to go with a floor shifter. I bought the Hurst/Indy shifter from Summit, nothing fit but I was able to make it work by modifying the hardware that was provided. I had to drill and cut the bracket they provided and it barely fit. The hole in the floor was already there from the previous owner. I could send pictures if needed.