I'm not a 40 expert, let alone an expert on anything. But food for thought...
I was, and still am a little, a died in the wool Rover guy. Pre-92 only, as they were "electronics free" ( no abs, all were coilers, no traction assist). Basically 3/4 ton trucks with creature comforts. Much more "soul" than my 80 could ever have. Just a flat out cool vehicle. That being said, I don't have to worry about that "coolness" ever getting in the way on a trip, around town, or even just trying to get out of my driveway in the 80.
My point? I love vehicles with personality. Hell, I have a tricked out vespa for crissakes. BUT, if I were to buy a 40, I wouldn't touch one that hadn't been gone through by someone else already, or hadn't been kept up well, and I would expect to pay upwards of 9~15k for one. To me, the up front pain of purchase would make the "coolness" that much more worth it.
As for cj/yj/tj's, the quality control just isn't there. It is after you have replaced everything, and that can be cool, but I have never seen one I would own that hadn't had axles/tranny/t-case/steering/top swapped out. The 6 cylinder motor is a beast, and quite good imho, but the manual tranny's leave a lot to be desired.
As for 40's, I have always been amazed by the durability and strength of stock 40's. I have been in many areas of the world, and I have seen a bunch of stock 40's and LR's, but NEVER did I see heeps in these places except m141's.
If I were looking for a fun convertable type wheeler, I would by a disco, rangie or 60/62 and cut the top off and rhino-line the interior, or a 84-85 four-runner with a soft top. The only jeep I would buy for this purpose would be a commando. They are cool, cheep, and fun, with no real mechanical shortcomings other than axles, and those are bolt ins from anything with 44's.
j