It may be ok height wise. Bigger is always better but I wouldn't keep them in a cage with an inch or more bar spacing. I know alot of people who have lost tiels thinking 1 inch bar spacing was ok. They can get their head stuck. The max should be 5/8 of an inch. They like to climb and be up high so height is good and width should be wide enough for them to stretch their wings. The cage I have my breeding pair in now is 30 inches high 23 inches wide and 19 inch depth. I also have their 3 babies in there and its still a good size but once they are weaned I am moving the babies to their own cage.
I have a 30x30x43" cage with 1/2" bar spacing for my two. With the stand and play top its taller than I am! Get the biggest cage you can.
That flight cage upthread is nice too, I've seen it in person and two tiels would probably be very happy in there!
I also have 2 of these cages. I used to keep 2 conures in one but after 8 months of being inseparable the male started plucking the females tail feathers out so I bought another one and separated them. She is much happier with this arrangement. keep in mind that even if they once loved to be together things can change and then you may have to run out and buy a new cage ASAP
P.S. Keep in mind you need plenty of perches and toys to fit and still have room for both birds... in my opinion the first cage would be too small for two cockatiels.