Trunk floor pan

If the car is going to have new 1/4 panels put on, cut a hole in the side of the 1/4 and slide the new pan in.
Easy job, but just time consuming to get the old pan out, I have found a grinder and a air-chisel works the best to remove old sheet-metal.

No need to. It fits right in the trunk opening on an A body.
And that wouldn't work anyway. You cannot put it in from the side