vtec swap for 91 gs

has anyone ever done a vtec swap on their integra? I am thinking about trying to do one but i want to know what im getting myself into if i decide to go for it. what all is involved?

http://www.g2ic.com/tegtips/engine/15.html

any good ideas where i can buy a vtec for my 91 integra gs?

search.

As stated, search, this has been discuss so many times now with many many write-ups. And post in the correct section. Reprogramming and Tuning is not for questions about engine swaps.