Cragar lug nut size for 71 Swinger?

First, we have to know if they are old style cragars or new.
The old ones, either unilug (fits two different bolt patterns) or single, used mag style shank lugs. The new ones use conical seat lugs.
The old style can probably use your stock studs,t he new style usually need new longer studs.
Next we need to know bolt pattern. 5 on 4 has 7 /16 studs, and might be left hand thread on the driver's side. If they are 5 on 4 1/2, they're 1/2 studs, less likely to have lefts on the left, but possible.