help me to understand cams

What causes a engine to lope/chop at idle is really a combination of several things, including the engines size. Tighter lobe separation, duration (total and at .050" lift) and valve lift and engine size are the 4 factors that affect it most. A cam that idles pretty choppy in a 273 might idle perfectly smooth in a 408 stroker because larger engines "eat up" duration. That only answers part of your question. Reading the Comp cams info will answer a lot of other questions.

In any case your always best off having a cam custom ground for your particular application by a reputable cam grinder rather than try guessing what might work, unless you have a lot of experience with engines and cams. I have used both Racer Brown and Bullet cams with real good results and there are several others out there that are good. Maybe some others will chime in on who they like.