So we just pryed and/or cajoled the seat out of our '51 3600 and yep there is a bunch of rust in there along with a couple of thru-holes. Looks like somebody did a wham-bam fix up a few yrs/decades ago by tacking on some flimsy sheet metal as well. Our question is... where to start. I'm sure we have to cut/grind back to untainted metal so my question more specifically is how. Is it best to take the cab entirely off for this? Just start grinding w/ cab in place? How risky is doing the latter (hitting other vital structures beneath the cab?? Hope you fellas don't mind these beginners questions and thanks.

1951 Chevy 3600