My buddy has had that same article hanging on the wall of his shop for like 8 or 10 years now. I look at it every time I go there.
There are quite a few street legal trikes out there and it is totally do-able. I saw one in person here in Mass. It was a CB750/350X mix, and it was really nicely done.
There was also an XR or an XL, either a 600 or a 650, I can't remember which, up in New Hampshire not long ago. I'm pretty sure Tanks350X here on the boards has pictures of both of those.
85 Tri-Zinger 60
85 ATC250SX
86 ATC250SX
87 ATC250SX
02 XR650L conversion
84 ATC 480R