I offer a suggestion: I did this job a couple of years ago, and I don't remember if the tensioner is held on by bolts or nuts, but if bolts, be sure you have the right ones and they are not too long. If you get the bolts mixed up and try to use ones that are too long, they will bottom out in the holes and you will think you have them tight, but alas! not tight, therefore oil leaks. I did not have any trouble whatsoever installing the new tensioner, no leaks, and I am a rank amateur. Be sure it is not cocked and is correctly seated in position.
Another suggestion to anyone contemplating this job: I bought a spring compressor and removed all the rocker arms; that way there was no risk of the valve spring pressure trying to turn the cams while I was working on it. Just keep up with where they came from and put them back in the same place.
Suggestion #3: be sure to insert the center tie plate in the master link. I almost left it out; EGAD! I wonder how many amateur chain replacements have ended in disaster down the road because of this. Slow down and think.
Good Luck, it's a beautiful car.