Orion would still take years to get to the closest star. And to say that their equipment would work as long as it needed to without repair or ability to repair....
If I remember the orion was the slowest of a bunch of different versions of spacecraft, that wouldn’t go above .02-.04c.
And if it was the version that used nuclear explosions to detonate behind it to push its driver plate, how many of those would they have, and how many could they carry before running out? The other thing was that it had to be very heavily shielded because of the nuclear explosions it used to propel it.
One could put a lot of spares on a 40MT spacecraft. Or to put it another way - how much stuff can be loaded on 256 supertankers?
Don’t remember any other craft proposed in 1963.
Water was the shielding - millions of tons of it. Same for cosmic ray shielding.