I believe the Del-alum comes in 2 sizes for the early Mustangs, did you receive a mixed set?
If not, then it seems one of your Global West spring eyes is not in tolerance.
If your stuff is new, than you might be able to work out an exchange.
If warranty is not possible, personally, I think I would make a replacement outer bushing to the OD you need for the spring. Any machine shop should be able to easily copy it, if you don’t have a lathe. Only difference will be that it won’t be blue, unless you paint it or send it off to be anodized.
My Del-a-lum set, on the rear frame shackle outer bushing, I had to turn the outer OD down to fit the aftermarket Dynacorn rear frame bushing bore. Just par for the course when mixed parts are combined.