Wolverine does seem make the best choice for the time traveler. I mean for one thing he's basically immortal, so it's not such a big deal if it's a one-way trip. He just gets to drink beer and stare at people for a few decades while waiting to catch up to the "present". Of course if he changes history, his "present" won't be there anymore so then there'll still be two Logans...Oh well.
But yeah, either way I think future Logan would require a lot less arseing around than trying to introduce 70's Logan into the mix. He's not the same character at that point in time and audiences may get confused otherwise.