I had a 65 and did the same thing. Hurst made 1 but I'm not sure if they still do. I was in school and and didn't have much money so this is what I did. Take seats out and leave your front carpet loose. Mount trans with shifter arms. Use a long punch and mark floor where the shifter will go through. Then from top side, Drill a 1/4 inch hole through floor. I'm not really sure what size hole I wound up with, but I used the boot and ring as a guide and then keep removing just enough to have clearance for shifter. With shifter mounted, I got 2 sheets of poster paper. I used the 1st one to mark, cut, bend, until I thought I had it so it would work(be sure to leave 1 inch all around so you can bend a 1 inch edge at 90 degrees so you will have something to mount it with). I then traced it to the 2nd sheet and cut it out. Then I bent it and did a little more until I had it right. Then I took 1/2 of a 50 Chevy hood( so I guess Chevys are good for something) traced the 2nd sheet on the hood and cut it out with an air chisel. Then I used a vice and 1x4 to bend it to shape and then had it welded. I used a ball peen hammer to make sure it matched the floor contour. I used 1 inch calking strips and collared self tapping sheet metal screws to mount. If you made it as low as possible and as small as possible, you should be able to remove the jute backing around the hump, and stretch your same carpet down, put your seats in and bang some gears. This might sound odd, but it worked on my 65 in 65. Hope this helps.
