yeah pretty much what they said....
I would add that "long throw" or long "cone excursion" speakers usually will totally change the "speaker plus box" tuning compared to the originals, and might not work well if just dropped into a cabinet.
They could flap and fart horribly or they might be better than the original ones, no way to tell without doing the calculations.
Since many "long throw" or long excursion speakers are sub woofer types, they might not be too hot for instrument use, either.
I think you would be better off to choose a complete system (cabinet & speakers) on tone and power handling, and not worry too much about how it got that way. If it sounds good, you can move it OK, and it doesn't blow up, what more is there to want?
Its about how they sound, after all. Tech stuff is a trap...good to know enough, bad to get too far into details unless you have to or that's where you are going instead of music.