ok. just wondering. as long as the bushings are in good shape there shouldn't be too much side to side movement. some suspensions seem to have lateral movement built in due to short panhard bars or whatever. as long as you are happy then thats what counts. a tire or wheel could be swapped out later if there is a problem, it just costs every time you do that.
it is good to get a dimension on the box from the outside to the outside of the actual box part, and then an actual inside to inside from side to side on the actual fenders when mounted. then draw that out and also draw an axle under there with the dimension from each axle flange to axle flange. then add the tire width and how it fits between the box sides and the fenders. when you are all done you will know the back space needed for the wheels and you can compare that to the wheels you have. if the truck is up on stands with the wheels off you can use a plumb bob from all the points needed and mark the floor below. then take dimensions from those marks.
I use this site for tire size comparison and actual widths. if you look down on the left side there are other calculators on the site too.
https://tiresize.com/comparison/
this one shows the drawing like I was trying to describe above. it also talks about scrub radius etc if the offset on the front axle is changed from the stock offset for that particular suspension set up.
https://www.wheel-size.com/calc/
what I do when for a ballpark dimension for checking the width is simply inflate the tire to max and put a straight edge on the sidewall vertically, both sides, then mark the floor on each side where the straight edge hits the floor. move the vehicle out of the way and measure between the marks. it may be off a little from the slight bulge in the tires, but if it is that tight of clearance then I don't wanna use that combo of tire/wheel anyway. i ruined enough tire sidewalls and fender lips due to ture rubbing around a corner or over a bump.