You've got three options on the wingtips. Mark IIs JT195 thru JT424 were delivered with the original Navy wing tips; most of these aircraft were later modified with the short wing tips, reducing the total span by about 10-3/4 inches. JT425 thru JT554 were delivered with the factory-installed short tips.
Even later, all of these aircraft could have been modified with the "short short" wing tips, reducing the span a further 2-1/2 inches and giving that squared look seen on Mark IVs.
Since you're planning a what-if, you can chose whichever tip pleases you most!
Cheers,
Dana