Rather than trusting some measurements you got online, you should consider measuring your car.
That way, any subtle differences resulting from your car's long history will be taken into account.

The typical way is to measure from center of the where the rear u-joint cap will be, to the center of where the front u-joint cap will be, with the front yoke slipped out of the transmission about 3/4".

Better yet, get the recommendation of the shop doing your driveshaft on how to do this measurement.
(But I bet it will be close to what I just described.)