Hi AJ & all; You have found a great group for help, but you will have to acquire patients. A few things you may already know. JE pistons are expensive & usually a sign of a quality build. I would guess that you have "a 350" engine bored .030" over yielding 355" inches. Unlikely some one would retained the 4.00" bore & spent big money on JE pistons? Cams, lift is how far the valve lifts off the valve seat usually in inches .502" (a hair over a 1/2" inch). Duration is how long the valve is open either letting air-fuel in or exhaust out of the cylinder during a full turn of the lobe (circle). The intake & exhaust cam lobes don't need to be identical & often aren't. All the engine & drive line parts have to be a team to function at their best. Mis match a part or two & have a disappointment. Timing & carb tuning are the end game.
START with timing as cost is LOW & results are BIG. Learn about your distributor & how it works. How much timing can your combustion chambers support & how soon can that advance start? Then to the carb, & it has to be sized to the engine, compression ratio, intake (manifold) & intake runners (heads). At that point the cam will play a big part (how far it opens the valves). Next is the vehicle weight & finial drive ratio (rear end) that will dictate how much carb & type of carb that will perform best. And last the torque converter will have to be loose enough to let the engine idle freely at stop. Then & only then you gotta ask your self how loose do I want this converter for my type of use (street, drag, Auto-X, road course, drift) Then buy the converter. Start at the distributor, Ole' Bob.
Ps: It's impossible to have a duration of 502* as a circle only has 360*