Yup, you have to make a new tunnel. The tremec sits higher than the ol" A833. Search my thread and see what I did. Worked out pretty well. :) Only need about an inch. When you're done, it's not a noticeable difference.
A body and B body will be a little different of course. Here is a series of pictures showing the tunnel mod, console fitment and shifter position. We ended up moving the console brackets back a little which will limit how far forward the seat will move. Seats are in rear most position in the pictures.