Kai,
I'm not sure what type of trailer you're actually getting. Airstream didn't make a trailer called a Safari in 1994. They made Safari's from the mid 1950's thru 1979. During this time the name Safari designated the length of the trailer as well as how it was outfitted. Safari's were marketed as 22' long until
1968 and then 23' long starting in 1969. The true length may have been up to a foot longer (or shorter?) than the marketed length. The amount the true length varied may have changed over the years.
Anyway, Airstream then next made a Safari starting in 1997 in the 25' length. At this time the name Safari designated only a trim level and over the next several years Safari's were available in additional lengths varying from 16' to 30'.
So, I'm not sure what to advise you on trailer dimensions, because I don't know what you actually purchased. If by chance it is the trailer in your avatar picture here on the forums, that trailer is a 1969 to about 1974 model and it appears to be longer than a Safari of that era. I'd guess it as a 27' Overlander from the photo.
Anyway, as far a trailer widths are concerned, I believe they were pretty much consistant from 1969 thru 1995. During this time the exterior width I believe is generally listed as 8' even (but may have been 7' 11.5" in reality). In 1996, all Airstreams 25' and longer got wider to about 8.5' (actually 103.5 inches if I remember correctly). Those shoter than 25' remained about 8' wide. Before 1969, Airstreams were narrower, about 7.5' wide in most, but not all cases.
As for length, they generally run from 1 to 12 inches longer than the advertised length, but there is no standard rule as to how much more.
I think the trailer heights varied a bit over the years too. And the presence or absence of an Air Conditioner (and which one) makes a big difference in the height dimension. The only thing I will say with some certainty about height is that they should generally be under 10' tall, even with an air conditioner.
Now, since you mention that your trailer is a 1994 model, I happen to have a 1994 Airstream Trailer catalog, so I'll quote you some values:
Width: 7' 11.5"
Exterior Height: 9' 7.5" (with A/C)
Actual Lengths:
21' Model: 21' 10"
25' Model: 25' 9.5" or 25' 11"
28' Model: 29' 0"
30' Model: 30' 9"
34' Model: 34' 10" or 35' 1"
If your trailer is not a 1994 model, these numbers should still be within a few inches.
I hope this information helps. Good Luck!