On my late 65, which is the same...
I had to cut 3/8" off the passenger side, and a little more than that in the front... almost 1/2" there.... I then made new mounting holes and custom fitted a cover... was not easy, since I had the engine and tranny in the car, the shifter was dropped down under the tunnel and I cut and fit mine that way, not perfect...
it is a very tight fit in there all the way around!
but worth the effort.