your numbers don't look right. Near as i can tell from the parts manual, it should be 45.85" with 7290 joints or 45.79 with 7260 joints. Are you measuring center to center? Your buddy might have a 904 trans or a smaller rearend than yours. Either would need a longer driveshaft than yours. Even spring arch, ride height makes a difference.

Safest way is to measure what you need and go with it. Lot of tolerance in these old cars and over 50 years of people interchanging parts that are not exactly correct.
Or not even close to correct.
.