On my Duster after I put in the frame connector I noticed that I got a bit of flex in the front from the firewall forward. I added some down bars that are welded to the fire wall down to the front of the frame rails. This made a big improvement with the flex. Also my frame connectors are mounted to where the leaf spring were bolted to with a about a 10" X 6" - 1/16" plate welded over the frame rail and the connector to tie them together and the connectors are welded up through the floor.
Tonight I was working on my Valiant and I noticed that when I put the stands under the front frame rails and let the jack down that I got some flex on the nose of it too. I don't want to install down bars like I did on my Duster, just think it won't look right on this car. So I'm going to see if I can come up with some type of bracing to do the same thing that can't be seen or isn't as noticeable. My Valiant is being build more as a handling car. I do have a 1 1/4" round bar welded in the front from frame rail to frame rail under the radiator to help stop twist in the front.