Here's the catch. Chrysler's published cam specs are unique to Chrysler.
A '71 340 will still have the 340 valves regardles of head casting, and should have the higher compression pistons.
There's engine decoding info in the 'articles' section of the forum.
Unless you have a particular goal and plan, I'd get it running and shake out the issues. Then make whatever mods float your boat.
Depending on what can be done under Calif. smog rules, it will run a little better with a distributor advance curve similar to those that came from Mopar Performance. Basically it allows using a pre-CAP initial timing without jacking up the timing above idle.
Headers will make a noticible difference, but are a royal PIA. Compared to a maverick engine bay, the Demon will seem roomy. However the T-bars make snaking the exhaust relatively challenging. Off the shelf there's really just two choices of manufacture, Dougs or TTI.