Dart, I believe that the car I mentioned is my next target (or victim as it may be). The early to mid- 1980's XJS's appeal to me, mainly as the last of the pre-Ford true Jaguars. Not that this is necessarily a good nor a bad thing, I'm speaking from the standpoint of what I would believe to be more collectible in the next decade or so. I would have no problem with the V12, if it had been well-maintained, nor a problem with the 6 cylinder, having known the 4.2 and the later 4.0 to be a solid drivetrain. I think the prospect of a mid-1980's V12 would be my choice.... something about the 6 cylinder in the XJS, though a great engine, seems wrong.... if I buy an XJS, I'll definitely drive both, but why not go for the larger engine (mainly out of trying something new). Check out the H.E. models I mentioned, I don't know enough about them to caution or to steer you toward one. Of course, to answer your question, the topless V12, low-mileage, would be my choice. But, there is something classic about a solid coupe version. The convertibles at some point were I believe completed here in the states, and at some other point were done in England at the factory, or so I was told. I would prefer on that had come from Coventry as a convertible, and not farmed out to another company for the conversion, simply for purist reasons I guess. If I do end up with the '85 XJS, which is the plan in the coming months, I'll hopefully be better educated on the model(s) than I am now.
As a side-note, when I was in high school, my doctor restored his BRG 1976 XJS fully before selling it to purchase a 50th Anniversary 300ZX. It was nothing short of awesome in its ride and sex appeal.... If you're not too set on a convertible, expand your search to one of the originals, you may fall in love with an early model. His son and I snuck it out, neither of us with a driver's license, and tore up the town, luckily not the car!
I hope you get some more educated replies regarding the 5.3L, but in the meantime do your research. The model page for the XJS at JCNA's site may help:
https://www.jcna.com/library/news/2005/jcna0206.php
Best wishes,
Brian /ubbthreads/images/graemlins/cheers.gif