Posted once before but need suggestions

You're in luck. The 71 through 77 /6s have the best camshaft Mopar installed in it. The specs on the cam are 244º/244º/26º with lifts of .406/.414. Mopar used to make a pair of camshafts for the engine, but the specs on the current models look like they are using repackaged Comp Cams. Comp Cams makes 4 cams (2H, 2S) that are stock item for them. (264º/264º/?? .440/.440.)A few years back, the guys over at Slantsix.org came up with a group order from Sig Erson. IDK the specs on it.
Good luck finding headers for the slant six. IDK if Hedman has produced any for the /6 in this millennium. There is a group in Australia that is making a set that lends itself very well for dual exhausts. http://www.ebay.com/itm/slant-6-mop...six-/371184135767?hash=item566c4c6e57&vxp=mtr . Dutra Duals are a good choice, too.
Another you might consider are made by Moparsnmore.us/exhaust.html. These are like the Dutra Duals but with larger passages. The guy who makes them got roughed up here and over on slantsix.org essentially for making performance claims at the time without providing instrumented tests to back them up. Look at them as an oversized Dutra Duals and you'll have realistic expectations. I've been using a single outlet product in combination with a 2¼" exhaust for the past six years on a street car with no issues.
One of the things to consider when making changes to the exhaust and intake, especially if you live in a northern climate is having a provision for heating the carburetor during when the engine is cold. With my setup the engine is hard to keep lit until the manifold warms up a bit.
If you can't find a 2bbl intake, try AussieSpeed. The runners on their manifold are longer than the Super Six, so you'll need a kickdown cable.
I left the /6 tranny alone in my 73. My 72 runs a 904 with a TransGo TF2 shift kit in it. It firms shifts up nicely. For what it does, it was a good change to make IMHO.