what to do?, upper b/j loose fit

I;m doing a disc brake conversion on my son's 74 Duster, I have the upper a arm's, spindle's, rotors, etc from the donor, I am replacing the upper a arm bushings, and upper and lower ball joint's in the new donor a arm's, one of the old upper b/j's was stubborn to get out and so upon re-installing the new b/j's one side threads is fine the other is a loose fit, any fix's?, thinking of maybe some tack welds at the top of the joint?, or I have heard the upper a arms on the existing drum set up, being as it is a 74 might be the same as the disc, so maybe I could use the original?, maybe there is an oversize b/j?,I was trying to have everything ready and bolted together for a quicker swap, thanks