I had a '64 Chevy C20 with the floor-mounted trans e-brake. I used a floor shifter boot designed for a '67-'68 Chevy truck. I have also used this one for the transfer case shifter and floor shifter on a '66 Chevy K10. They look great and work great.
I got them from
www.classicparts.com
If you are looking for a solution, this is great, but it is not factory.