On the phone, Martin at Jule described a frame test which is described on their website as well:
"The easiest way to do this is to place a jack under the rear outrigger by the rear of the door, slide the jack under the chassis where the out rigger meets and jack the car up. Check your door gap, if it opens, the main rail structure is worn. Look at the front tire and rear tire, if they are resting well on the ground this will indicate the torque rigidity is failing."
I asked what qualifies as a door gap opening, and (while I don't have my notes in front of me) I believe he said if it grows 1/4", that would indicate a problem.
Also, he said that his springs come with longer U-bolts, so that makes installation somewhat easier than others have found. Also, someone earlier in this thread said they had to drill out a hole (I forget its name) to receive the spring center bolt, but I guess this is only an issue with early Healeys, and the BJ8 won't have to be modified in even this minor way.
He also mentioned that the arc of his springs will be different than other vendors, because they don't need to be preloaded. Some have expressed challenges with getting a standard new spring installed because it needed to be loaded during the install. I guess his springs, because they are a less arched shape, don't need to be forced in during installation.
Sorry if I sound like an advertisement. I don't know Martin at all, but his love of Healeys was clearly communicated during out conversation.