I concur on the Tuffy. I currently have the 8" wide installed on my '77. Used to have a 10" installed (and it is currently for sale!! $150 you pay the shipping) but I found that it was a little bit of a tight fit. Both front seats just touched the console, which wasn't a problem. The problem was my a$$ was a little too wide for the set up.
Caused me to sit a little off center on the seat and that was not comfortable/stable.
If you are "normal size" a 10" is great. If anyone has ever referred to you as 'Husky", "Robust" or "Thick" then go with the 8".