Here’s a few pics of my 65 I did two years ago . Brace cab real good . A cart is nice to roll cab around on . Then I did kick panels , toe boards etc . Like others have said you will have to add 3/8” of an inch give or take to inner rocker area . I didn’t know this and fought with my rocker fitting and door/fender alignment what a waiste of time. My doors are very tight to rocker where I should of lowered rocker more and added that material in on inner floor . When I did the wife’s 61 a year later I seen a post where guys were adding material to that inner floor/rocker area and things line up nice. Live and learn
Have fun. I have a 72 that is going to get same treatment here soon least I’m getting quick at it now lol