We went from an '08 Sahara off the showroom floor to a '14 Rubi (white - wife picked the color) off the floor...the 3.6L was a definite upgrade. That alone was worth it.
After putting over 100k on the '08, about 50k on the '14, I sold my Scrambler and wanted something newer and as built as the Scrambler I just let go...so I started putting a build sheet together on the '14 we already had...then I happened upon another '14 with everything on my list, and Anvil. Bam, I sold my Corvette and the white Rubi, bought the wife a nice TJ, and snagged a '14 Rubi on D60/80 and 40's. Personally, I'm happier w/ it than I ever would have been putting years into a build and paying for every part.
Have you considered searching for one that already has what you're looking for on it? Not only save you some money on the build end, you get to use it NOW, right away, vs spending all that garage time on it. I know some live for that, Lord knows I used to, but situations change, etc. Of course, might be a tough find if you're looking for JUST that color...but Anvil is pimp, super glad I found mine.
Anyway, good luck, you'll really like the 3.6 over the 3.8.
B