Welcome from Arkansas!
I used a set from XV if memory serves. That was in 2008 or so. Some grinding but, not much. Fit the floor pretty close out of the box.
I put these connectors in place, as tight as I could get them. Here are some pictures. Where I have the popsicle sticks there is a 0.180" gap, those are some of the worst areas. The front end is horrible .75" along the area near the torsion bar. The rear inside has a nice radius that supposed to fit the rear sub-frame. The raduis matches, it's only off by an inch, haha. I notched the floor pan where the front pan meets the back pan, where I put yellow tape on the outside. That was the first major interference. The tape on the inside is where they have a nice notch that would fit right around the area I notched, were it on the correct side of the connector.
So Xcudame was right, extensive grinding would be required on these connectors to make them fit so you could weld the 10ga connector to the 20 ga floor pan.
gzig5 carve out some extra time, I'm sure you will see the same thing.