New floor pans

Going to be replacing both floor pans in my 75 maro.
Full length, right and left.
Anyone ever done this, if so, any tips.
Then onto the rocker panels and rear quarters.
just worried about the structure of the unibody when we cut out the old floors and rockers.
thanks for any info.....

Nah, posted the ? like last month when I realized my pan was cracked. Not much luck in reply aside from band aide it and forget it.

never actually done it before... only seen it on tv... just make sure you tack weld in some braces to keep the car straight when you start cutting at it