Whichever Jaguar (or any car) you end up getting, make sure there is something about it that you absolutely (irrationally) love. There may be times when that love will be all to keep you from burning it and the garage it sits in right down to the ground. (Damn! I just fixed the "B" and now the "C" doesn't work.)
One advantage to the model years you mentioned is the lack of high-tech electronics ("no user serviceable parts inside"). Someone with mechanical aptitude can accomplish much of what is required to maintain or improve cars from the 60's or earlier, and many are well-, or best-suited to your Sunday drives. By the way, a good thing to consider in your search for a Sunday-driver...what's your climate like and will it be comfortable for you, and it, when you do take it out for that drive...? A need for A/C may push you well out of the 60's era Jags, even into the next century, as David suggests.
Half the fun will be the hunt...and having some rejects or un-reachables to compare your eventual 'true love' to.
Go get it!
ST.