What Rusty64 says is true. I have my 1965 seat all the way back to where it touches the back of the cab. Removing the tank would not change a thing. I've never sat in another 60-66 with different seats but I would guess that a different seat design might give you more leg room (thinner seat back perhaps).
I did shorten my steering column for better driving comfort. I prefer having the steering wheel closer to the dash.
I suggest you find someone with a comfortable 60-66 and sit in it to be sure. Then copy theirs.
Last edited by Lugnutz; 01/10/2017 3:58 PM.